Prenatal organophosphate metabolite and organochlorine levels and performance on the Brazelton Neonatal Behavioral Assessment Scale in a multiethnic pregnancy cohort

Endocrine Disruptors in Pregnancy: Effects on Mothers and Fetuses-A Review

Background/Objectives: Endocrine disruptors are ubiquitous agents in the environment and are present in everyday consumer products. These agents can interfere with the endocrine system, and subsequently the reproductive system, especially in pregnancy. An increasing number of studies have been conducted to discover and describe the health effects of these agents on humans, including pregnant women, their fetuses, and the placenta. This review discusses prenatal exposure to various endocrine disruptors, focusing on bisphenols, phthalates, organophosphates, and perfluoroalkyl substances, and their effects on pregnancy and fetal development. Methods: We reviewed the literature via the PubMed and EBSCO databases and included the most relevant studies. Results: Our findings revealed that several negative health outcomes were linked to endocrine disruptors. However, despite the seriousness of this topic and the abundance of research on these agents, it remains challenging to draw strong conclusions about their effects from the available studies. This does not allow for strong, universal guidelines and might result in poor patient counseling and heterogeneous approaches to regulating endocrine disruptors. Conclusions: The seriousness of this matter calls for urgent efforts, and more studies are needed in this realm, to protect pregnant patients, and ultimately, in the long term, society.

Prenatal endocrine-disrupting chemicals exposure and impact on offspring neurodevelopment: A systematic review and meta-analysis

PURPOSE

Considering that endocrine disruptors have certain effects on fetal growth, we conducted a systematic review of epidemiological literature to elucidate the correlation between exposure to endocrine-disrupting chemicals during pregnancy and the neurodevelopment of offspring.

METHOD

We systematically explored PubMed, Web of Science, and CINAHL databases from inception to April 4, 2023. References from pertinent studies were reviewed, and data regarding the link between maternal prenatal EDC exposure and offspring neurological development were compiled. A domain-based approach was used to evaluate studies of neurodevelopmental effects in children ≤3 years old by two reviewers, including cognition, motor, behavior, language, and non-verbal ability.

RESULTS

A comprehensive search yielded 45,373 articles, from which 48 articles, involving 26,005 mother-child pairs, met the criteria and were subsequently included in our analysis. The results revealed that EDC exposure during pregnancy had a significant impact on offspring neurobehavior development, especially in cognition, motor, and language. Our findings indicated adverse associations between prenatal exposure to metals and offspring cognition (before 12 months: β coefficient: -0.28; 95 % CI, -0.50 to -0.06; 1-3 years old: β coefficient: -0.55; 95 % CI: -1.08 to -0.02). Furthermore, metals (β coefficient: -0.71; 95 % CI: -1.23 to -0.19) and phthalates (β coefficient: -0.69; 95 % CI: -1.05 to -0.33) exposure exhibited detrimental effects on motor development from1-3 years old, while poly-fluoroalkyl substances were linked to the disruption of offspring language development (β coefficient: -1.01; 95 % CI: -1.90 to -0.11) within this timeframe. Additionally, exposure to EDCs during pregnancy had a negative impact on cognition development among girls from 12 to 36 months of age (β coefficient: -0.53; 95 % CI: -1.01 to -0.06).

CONCLUSION

Prenatal exposure to EDCs, especially metals, phthalates and, poly-fluoroalkyl substances, was associated with disrupting the development of offspring neurobehavior in the short and long term. Additionally, cognitive development showed gender differences due to prenatal endocrine-disrupting chemicals exposure.

Prenatal particulate matter exposure is linked with neurobehavioural development in early life

BACKGROUND

Early life exposure to ambient particulate matter (PM) may negatively affect neurobehavioral development in children, influencing their cognitive, emotional, and social functioning. Here, we report a study on prenatal PM2.5 exposure and neurobehavioral development focusing on different time points in the first years of life.

METHODS

This study was part of the ENVIRONAGE birth cohort that follows mother-child pairs longitudinally. First, the Neonatal Behavioral Assessment Scale (NBAS) was employed on 88 newborns aged one to two months to assess their autonomic/physiological regulation, motor organisation, state organisation/regulation, and attention/social interaction. Second, our study included 393 children between the ages of four and six years, for which the Strengths and Difficulties Questionnaire (SDQ) was used to assess the children's emotional problems, hyperactivity, conduct problems, peer relationship, and prosocial behaviour. Prenatal PM2.5 exposure was determined using a high-resolution spatial-temporal method based on the maternal address. Multiple linear and multinomial logistic regression models were used to analyse the relationship between prenatal PM2.5 exposure and neurobehavioral development in newborns and children, respectively.

RESULTS

A 5 μg/m³ increase in first-trimester PM2.5 concentration was associated with lower NBAS range of state cluster scores (-6.11%; 95%CI: -12.00 to -0.23%; p = 0.04) in one-to-two-month-old newborns. No other behavioural clusters nor the reflexes cluster were found to be associated with prenatal PM2.5 exposure. Furthermore, a 5 μg/m³ increment in first-trimester PM2.5 levels was linked with higher odds of a child experiencing peer problems (Odds Ratio (OR) = 3.89; 95%CI: 1.39 to 10.87; p = 0.01) at ages four to six. Additionally, a 5 μg/m³ increase in second-trimester PM2.5 concentration was linked to abnormal prosocial behaviour (OR = 0.49; 95%CI: 0.25 to 0.98; p = 0.04) at four to six years old. No associations were found between in utero PM2.5 exposure and hyperactivity or conduct problems.

CONCLUSIONS

Our findings suggest that prenatal exposure to PM may impact neurobehavioural development in newborns and preschool children. We identified sensitive time windows during early-to-mid pregnancy, possibly impacting stage changes in newborns and peer problems and prosocial behaviour in children.

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.

Disparities in Toxic Chemical Exposures and Associated Neurodevelopmental Outcomes: A Scoping Review and Systematic Evidence Map of the Epidemiological Literature

BACKGROUND

Children are routinely exposed to chemicals known or suspected of harming brain development. Targeting Environmental Neuro-Development Risks (Project TENDR), an alliance of > 50 leading scientists, health professionals, and advocates, is working to protect children from these toxic chemicals and pollutants, especially the disproportionate exposures experienced by children from families with low incomes and families of color.

OBJECTIVE

This scoping review was initiated to map existing literature on disparities in neurodevelopmental outcomes for U.S. children from population groups who have been historically economically/socially marginalized and exposed to seven exemplar neurotoxicants: combustion-related air pollution (AP), lead (Pb), mercury (Hg), organophosphate pesticides (OPs), phthalates (Phth), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs).

METHODS

Systematic literature searches for the seven exemplar chemicals, informed by the Population, Exposure, Comparator, Outcome (PECO) framework, were conducted through 18 November 2022, using PubMed, CINAHL Plus (EBSCO), GreenFILE (EBSCO), and Web of Science sources. We examined these studies regarding authors' conceptualization and operationalization of race, ethnicity, and other indicators of sociodemographic and socioeconomic disadvantage; whether studies presented data on exposure and outcome disparities and the patterns of those disparities; and the evidence of effect modification by or interaction with race and ethnicity.

RESULTS

Two hundred twelve individual studies met the search criteria and were reviewed, resulting in 218 studies or investigations being included in this review. AP and Pb were the most commonly studied exposures. The most frequently identified neurodevelopmental outcomes were cognitive and behavioral/psychological. Approximately a third (74 studies) reported investigations of interactions or effect modification with 69% (51 of 74 studies) reporting the presence of interactions or effect modification. However, less than half of the studies presented data on disparities in the outcome or the exposure, and fewer conducted formal tests of heterogeneity. Ninety-two percent of the 165 articles that examined race and ethnicity did not provide an explanation of their constructs for these variables, creating an incomplete picture.

DISCUSSION

As a whole, the studies we reviewed indicated a complex story about how racial and ethnic minority and low-income children may be disproportionately harmed by exposures to neurotoxicants, and this has implications for targeting interventions, policy change, and other necessary investments to eliminate these health disparities. We provide recommendations on improving environmental epidemiological studies on environmental health disparities. To achieve environmental justice and health equity, we recommend concomitant strategies to eradicate both neurotoxic chemical exposures and systems that perpetuate social inequities. https://doi.org/10.1289/EHP11750.

Prenatal and Childhood Exposure to Organophosphate Pesticides and Behavior Problems in Adolescents and Young Adults in the CHAMACOS Study

BACKGROUND

We previously reported associations of prenatal exposure to organophosphate (OP) pesticides with poorer neurodevelopment in early childhood and at school age, including poorer cognitive function and more behavioral problems, in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), a birth cohort study in an agriculture community.

OBJECTIVE

We investigated the extent to which early-life exposure to OP pesticides is associated with behavioral problems, including mental health, in youth during adolescence and early adulthood.

METHODS

We measured urinary dialkylphosphates (DAPs), nonspecific OP metabolites, in urine samples collected from mothers twice during pregnancy (13 and 26 wk) and at five different times in their children (ages 6 months to 5 y). We assessed maternal report and youth report of externalizing and internalizing behavior problems using the Behavior Assessment System for Children, 2nd edition (BASC-2), when the youth were ages 14, 16, and 18 y. Because there was evidence of nonlinearity, we estimated associations across quartiles of DAPs and modeled repeated outcome measures using generalized estimating equations.

RESULTS

There were 335 youths with prenatal maternal DAP measures and 14-. 16-, or 18-y BASC-2 scores. Prenatal maternal DAP concentrations (specific gravity-adjusted median, Q 1 - Q 3 = 159.4 , 78.7 - 350.4  nmol / L ) were associated with higher T-scores (more behavior problems) from maternal report, including more hyperactivity [fourth vs. first quartile of exposure β = 2.32 ; 95% confidence interval (CI): 0.18, 4.45], aggression (β = 1.90 ; 95% CI: 0.15, 3.66), attention problems (β = 2.78 ; 95% CI: 0.26, 5.30), and depression (β = 2.66 ; 95% CI: 0.08, 5.24). Associations with youth report of externalizing problems were null, and associations with depression were suggestive (fourth vs. first quartile of exposure β = 2.15 ; 95% CI: - 0.36 , 4.67). Childhood DAP metabolites were not associated with behavioral problems.

DISCUSSION

We found associations of prenatal, but not childhood, urinary DAP concentrations with adolescent/young adult externalizing and internalizing behavior problems. These findings are consistent with prior associations we have reported with neurodevelopmental outcomes measured earlier in childhood in CHAMACOS participants and suggests that prenatal exposure to OP pesticides may have lasting effects on the behavioral health of youth as they mature into adulthood, including their mental health. https://doi.org/10.1289/EHP11380.

Influence of exposure to pesticides on telomere length and pregnancy outcome: Diethylphosphates but not Dimethylphosphates are associated with accelerated telomere attrition in a Palestinian cohort

Exposure to environmental pesticides during pregnancy is associated with adverse health outcomes such as low birth weight and impaired neuro-development. In this study, we assessed maternal leukocyte telomere lengths (TL) in Palestinian pregnant women and compared the data with urinary organophosphate concentrations, demographic, lifestyle and dietary factors, birth weight, body length, gestational age, and head circumference. Women with high urine levels of creatinine adjusted diethylphosphate(DE)derived pesticide metabolites DEP, DETP or DEDTP had shorter telomeres (p = 0.05). Women living in proximity to agricultural fields had shorter telomeres compared to women not living in proximity to agricultural fields (p = 0.011). Regular consumption of organic food was associated with shorter telomeres (p = 0.01), whereas the consumption of other vegetables such as artichokes was rather associated with longer telomeres. By contrast, urine levels of dimethylphosphate(DM)-derived pesticide metabolites DMTP and DMDTP were associated with lower birth weight (p = 0.05) but not with shrter telomeres. In conclusion organophosphate pesticides and living in proximity to agriculture are associated with shorter TL, likely due to higher consumption of contaminated fruits and vegetables and/or the transport of pesticides to non-treatment sites. DE and DM substituted pesticides seem to have different effects on telomeres and development.

Pesticides at brain borders: Impact on the blood-brain barrier, neuroinflammation, and neurological risk trajectories

Pesticides are omnipresent, and they pose significant environmental and health risks. Translational studies indicate that acute exposure to high pesticide levels is detrimental, and prolonged contact with low concentrations of pesticides, as single and cocktail, could represent a risk factor for multi-organ pathophysiology, including the brain. Within this research template, we focus on pesticides' impact on the blood-brain barrier (BBB) and neuroinflammation, physical and immunological borders for the homeostatic control of the central nervous system (CNS) neuronal networks. We examine the evidence supporting a link between pre- and postnatal pesticide exposure, neuroinflammatory responses, and time-depend vulnerability footprints in the brain. Because of the pathological influence of BBB damage and inflammation on neuronal transmission from early development, varying exposures to pesticides could represent a danger, perhaps accelerating adverse neurological trajectories during aging. Refining our understanding of how pesticides influence brain barriers and borders could enable the implementation of pesticide-specific regulatory measures directly relevant to environmental neuroethics, the exposome, and one-health frameworks.

Multiple neurological effects associated with exposure to organophosphorus pesticides in man

This article reviews available data regarding the possible association of organophosphorus (OP) pesticides with neurological disorders such as dementia, attention deficit hyperactivity disorder, neurodevelopment, autism, cognitive development, Parkinson's disease and chronic organophosphate-induced neuropsychiatric disorder. These effects mainly develop after repeated (chronic) human exposure to low doses of OP. In addition, three well defined neurotoxic effects in humans caused by single doses of OP compounds are discussed. Those effects are the cholinergic syndrome, the intermediate syndrome and organophosphate-induced delayed polyneuropathy. Usually, the poisoning can be avoided by an improved administrative control, limited access to OP pesticides, efficient measures of personal protection and education of OP pesticide applicators and medical staff.

Preconception exposure to malathion and glucose homeostasis in rats: Effects on dams during pregnancy and post-term periods, and on their progeny

Understanding the individual and global impact of pesticides on human physiology and the different stages of life is still a challenge in environmental health. We analyzed here whether administration of the organophosphate insecticide malathion before pregnancy could affect glucose homeostasis during pregnancy and, in addition, generate possible later consequences in mothers and offspring. For this, adult Wistar rats were allocated into two groups and were treated daily (intragastric) with malathion (14 or 140 mg/kg, body mass (bm)) for 21-25 days. Corn oil was used as vehicle in the Control group. Subgroups were defined based on the absence (nulliparous) or presence (pregnant) of a copulatory plug. Pregnant rats were followed by an additional period of 2 months after the term (post-term), without continuing malathion treatment. Fetuses and adult offspring of males and females were also evaluated. We ran an additional experimental design with rats exposed to malathion before pregnancy at a dose of 0.1 mg/kg bm. Malathion exposure resulted in glucose intolerance in the mothers during pregnancy and post-term period, regardless of the exposure dose. This was accompanied by increased visceral adipose tissue mass, dyslipidemia, unchanged pancreatic β-cell mass, and varying insulin responses to glucose in vivo. The number of total newborns and birthweight was not affected by malathion exposure. Adult offspring from both sexes also became glucose-intolerant, regardless of the pesticide dose their dams were exposed to. This alteration could be associated with changes at the epigenomic level, as reduced hepatic mRNA content of DNA methylases and demethylases was found. We demonstrated that periconceptional exposure to malathion with doses aiming to mimic from work environment to indirect contamination predisposes progenitors and offspring rats to glucose intolerance. Thus, we conclude that subchronic exposure to malathion is a risk factor for gestational diabetes and prediabetes later in life.

The relationship between prenatal exposure to organophosphate insecticides and neurodevelopmental integrity of infants at 5-weeks of age

Introduction

Organophosphate (OP) insecticides are among the most abundantly used insecticides worldwide. Thailand ranked third among 15 Asian countries in its use of pesticides per unit hectare and fourth in annual pesticide use. More than 40% of Thai women of childbearing age work on farms where pesticides are applied. Thus, the potential for pregnant women and their fetuses to be exposed to pesticides is significant. This study investigated the relationship between early, mid, and late pregnancy maternal urine concentrations of OP metabolites and infant neural integrity at 5 weeks of age.

Method

We enrolled women employed on farms from two antenatal clinics in the Chiang Mai province of northern Thailand. We collected urine samples monthly during pregnancy, composited them by early, mid and late pregnancy and analyzed the composited samples for dialkylphosphate (DAP) metabolites of OP insecticides. At 5 weeks after birth, nurses certified in use of the NICU Network Neurobehavioral Scale (NNNS) completed the evaluation of 320 healthy infants. We employed generalized linear regression, logistic and Poisson models to determine the association between NNNS outcomes and DAP concentrations. All analyses were adjusted for confounders and included creatinine as an independent variable.

Results

We did not observe trimester specific associations between DAP concentrations and NNNS outcomes. Instead, we observed statistically significant inverse associations between NNNS arousal (β = -0.10; CI: -0.17, -0.002; p = 0.0091) and excitability [0.79 (0.68, 0.92; p = 0.0026)] among participants with higher average prenatal DAP concentrations across pregnancy. We identified 3 NNNS profiles by latent profile analysis. Higher prenatal maternal DAP concentrations were associated with higher odds of being classified in a profile indicative of greater self-regulation and attention, but arousal and excitability scores below the 50th percentile relative to US normative samples [OR = 1.47 (CI: 1.05, 2.06; p = 0.03)]. Similar findings are also observed among infants with prenatal exposure to substances of abuse (e.g., methamphetamine).

Discussion

Overall, the associations between prenatal DAP concentrations and NNNS summary scores were not significant. Further evaluations are warranted to determine the implications of low arousal and excitability for neurodevelopmental outcomes of attention and memory and whether these results are transitory or imply inadequate responsivity to stimulation among children as they develop.

Metabolome-wide association study of the relationship between chlorpyrifos exposure and first trimester serum metabolite levels in pregnant Thai farmworkers

INTRODUCTION

Organophosphate (OP) insecticides, including chlorpyrifos, have been linked with numerous harmful health effects on maternal and child health. Limited data are available on the biological mechanisms and endogenous pathways underlying the toxicity of chlorpyrifos exposures on pregnancy and birth outcomes. In this study, we measured a urinary chlorpyrifos metabolite and used high-resolution metabolomics (HRM) to identify biological perturbations associated with chlorpyrifos exposure among pregnant women in Thailand, who are disparately exposed to high levels of OP insecticides.

METHODS

This study included 50 participants from the Study of Asian Women and their Offspring's Development and Environmental Exposures (SAWASDEE). We used liquid chromatography-high resolution mass spectrometry to conduct metabolic profiling on first trimester serum samples collected from participants to evaluate metabolic perturbations in relation to chlorpyrifos exposures. We measured 3,5,6-trichloro-2-pyridinol (TCPy), a specific metabolite of chlorpyrifos and chlorpyrifos-methyl, in first trimester urine samples to assess the levels of exposures. Following an untargeted metabolome-wide association study workflow, we used generalized linear models, pathway enrichment analyses, and chemical annotation to identify significant metabolites and pathways associated with urinary TCPy levels.

RESULTS

In the 50 SAWASDEE participants, the median urinary TCPy level was 4.36 μg TCPy/g creatinine. In total, 691 unique metabolic features were found significantly associated with TCPy levels (p < 0.05) after controlling for confounding factors. Pathway analysis of metabolic features associated with TCPy indicated perturbations in 24 metabolic pathways, most closely linked to the production of reactive oxygen species and cellular damage. These pathways include tryptophan metabolism, fatty acid oxidation and peroxisome metabolism, cytochromes P450 metabolism, glutathione metabolism, and vitamin B3 metabolism. We confirmed the chemical identities of 25 metabolites associated with TCPy levels, including glutathione, cystine, arachidic acid, itaconate, and nicotinamide adenine dinucleotide.

DISCUSSION

The metabolic perturbations associated with TCPy levels were related to oxidative stress, cellular damage and repair, and systemic inflammation, which could ultimately contribute to health outcomes, including neurodevelopmental deficits in the child. These findings support the future development of sensitive biomarkers to investigate the metabolic underpinnings related to pesticide exposure during pregnancy and to understand its link to adverse outcomes in children.

Organophosphate Insecticide Toxicity in Neural Development, Cognition, Behaviour and Degeneration: Insights from Zebrafish

Organophosphate (OP) insecticides are used to eliminate agricultural threats posed by insects, through inhibition of the neurotransmitter acetylcholinesterase (AChE). These potent neurotoxins are extremely efficacious in insect elimination, and as such, are the preferred agricultural insecticides worldwide. Despite their efficacy, however, estimates indicate that only 0.1% of organophosphates reach their desired target. Moreover, multiple studies have shown that OP exposure in both humans and animals can lead to aberrations in embryonic development, defects in childhood neurocognition, and substantial contribution to neurodegenerative diseases such as Alzheimer's and Motor Neurone Disease. Here, we review the current state of knowledge pertaining to organophosphate exposure on both embryonic development and/or subsequent neurological consequences on behaviour, paying particular attention to data gleaned using an excellent animal model, the zebrafish (Danio rerio).

Characterization of Urinary Pesticide Metabolite Concentrations of Pregnant Women in Suriname

Prenatal exposure to pesticides and the association with adverse health outcomes have been examined in several studies. However, the characterization of pesticide exposure among Surinamese women during pregnancy has not been assessed. As part of the Caribbean Consortium of Research in Environmental and Occupational Health research program, 214 urine samples were collected from pregnant women living in three regions in Suriname with different agricultural practices: capital Paramaribo, the rice producing district Nickerie, and the tropical rainforest, the Interior. We used isotope dilution tandem mass spectrometry to quantify urinary concentrations of biomarkers of three pesticide classes, including phenoxy acid herbicides and organophosphate and pyrethroid insecticides, all of which are commonly used in agricultural and residential settings in Suriname. We observed that participants residing in Nickerie had the highest urinary metabolite concentrations of 2,4-dichlorophenoxyacetic acid and pyrethroids compared to those from Paramaribo or the Interior. Paramaribo had the highest concentrations of organophosphate metabolites, specifically dialkyl phosphate metabolites. Para-nitrophenol was detected in samples from Paramaribo and the Interior. Samples from Nickerie had higher median urinary pesticide concentrations of 2,4-dichlorophenoxyacetic acid (1.06 μg/L), and the following metabolites, 3,5,6-trichloro-2-pyridinol (1.26 μg/L), 2-isopropyl-4-methyl-6-hydroxypyrimidine (0.60 μg/L), and 3-phenoxybenzoic acid (1.34 μg/L), possibly due to residential use and heavy rice production.

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.

Prenatal exposure to organophosphate pesticides and risk-taking behaviors in early adulthood

INTRODUCTION

Previous studies show evidence for associations of prenatal exposure to organophosphate (OP) pesticides with poorer childhood neurodevelopment. As children grow older, poorer cognition, executive function, and school performance can give rise to risk-taking behaviors, including substance abuse, delinquency, and violent acts. We investigated whether prenatal OP exposure was associated with these risk-taking behaviors in adolescence and young adulthood in a Mexican American cohort.

METHODS

We measured urinary dialkyl phosphates (DAPs), non-specific metabolites of OPs, twice (13 and 26 weeks gestation) in pregnant women recruited in 1999-2000 in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, a birth cohort set in a primarily Latino agricultural community in the Salinas Valley, California. We followed up children throughout their childhood and adolescence; at the 18-year visit, adolescent youth (n = 315) completed a computer-based questionnaire which included questions about substance use, risky sexual activity, risky driving, and delinquency and police encounters. We used multivariable models to estimate associations of prenatal total DAPs with these risk-taking behaviors.

RESULTS

The prevalence of risk-taking behaviors in CHAMACOS youth ranged from 8.9% for smoking or vaping nicotine to 70.2% for committing a delinquent act. Associations of total prenatal DAPs (geometric mean = 132.4 nmol/L) with risk-taking behavior were generally null and imprecise. Isolated findings included a higher risk for smoking or vaping nicotine within the past 30 days (relative risk [RR] per 10-fold increase in prenatal DAPs = 1.89, 95% CI: 1.00, 3.56) and driving without a license (RR = 1.74, 95% CI: 1.25, 2.42). There were no consistent differences by sex or childhood adversity.

DISCUSSION

We did not find clear or consistent evidence for associations of prenatal OP exposure with risk-taking behaviors in adolescence/early adulthood in the CHAMACOS population. Our small sample size may have prevented us from detecting potentially subtle associations of early life OP exposure with these risk-taking behaviors.

Gestational Exposure to Organophosphate Pesticides and Longitudinally Assessed Behaviors Related to Attention-Deficit/Hyperactivity Disorder and Executive Function

The brain’s prefrontal cortex directs higher-order cognitive and behavioral processes that are important for attention, working memory, and inhibitory control. We investigated whether gestational exposure to organophosphate (OP) pesticides was associated with these abilities in childhood and early adolescence. Between 1999 and 2000, we enrolled pregnant women in a birth cohort drawn from an agricultural region of California. We measured dialkyl phosphate (DAP) metabolites of OP pesticides in maternal pregnancy urine samples (13 and 26 weeks) and estimated associations with behaviors related to attention-deficit/hyperactivity disorder and executive function, assessed longitudinally; 351 families provided neurodevelopmental outcome data at any point when the child was aged 7–12 years. We assessed function across multiple dimensions (e.g., working memory, attention), methods (e.g., behavior reports, child assessment), and reporters (e.g., mothers, teachers, child self-reports). Higher gestational DAP concentrations were consistently associated with behaviors related to attention-deficit/hyperactivity disorder and executive function. For example, a 10-fold increase in gestational DAP concentration was associated with poorer longitudinally assessed Behavior Rating Inventory of Executive Function scores, as reported by mothers (β = 4.0 (95% confidence interval: 2.1, 5.8); a higher score indicates more problems), and Weschler Intelligence Scale for Children—Fourth Edition Working Memory scores (a 3.8-point reduction; β = −3.8 (95% confidence interval: −6.2, −1.3)). Reducing gestational exposure to OP pesticides through public health policy is an important goal.

Chlorpyrifos and other pesticide exposure and suspected developmental delay in children aged under 5 years: a case-control study in Phitsanulok, Thailand

Background: Developmental delay among children under 5 years of age is a serious global public health problem and much research has been carried out to find potential causes. Pesticides - especially organophosphates - are suspected to be one of the main causes of the problem.  This study aimed to investigate the association between pesticide use by the mother during pregnancy and preschool children development using a case-control study.

Methods: Data on prenatal and postnatal pesticide exposure of 442 children with suspected developmental delay, and 413 controls with normal development were included for analysis. The children were matched for gender, age, and residency. Data on pesticide exposure were collected via interview with the mother, and data on pregnancy outcomes abstracted from hospital records.  

Results: Chlorpyrifos exposure significantly increased the risk of developmental delay with an odds ratio (OR) of 3.71 (95% CI 1.03-13.36) for ever use of the pesticide, and an OR of 5.92 (95% CI 1.01-34.68) for postnatal exposure (p <0.05). Some other pesticides also had a positive association with developmental delay but none were statistically significant (p <0.05). Those pesticides were insecticide, fungicide, herbicide, and molluscicide. Individual pesticides with a positive association were glyphosate, paraquat, butachlor, methyl parathion (pholidon), savin, methomyl, endosulfan, carbosulfan, methamidophos, monochrotofos, mancozeb, and bordeaumixture.

Conclusions: This case-control study found that chlorpyrifos and some other pesticides exposure during pregnancy were positively associated with developmental delay in children aged under 5 years. Further research should be conducted to better understand this potential effects of pesticides on child neurodevelopment, and the public - especially those who plan to have families - should be informed.

Prenatal organophosphate exposure can cause adverse birth outcomes to humans

Organophosphate (OP) pesticides may accumulate in pregnant agricultural workers, resulting in adverse effects on the growth and development of the fetus and neonates. This study aims to evaluate a possible association between prenatal urinary OP metabolite levels among pregnant agricultural workers and birth outcomes of infants. This study also investigated the factors associated with urinary OP metabolites among pregnant agricultural workers. The spot urine samples were collected and analyzed for six OP metabolite levels. Birth outcomes data were abstracted from medical records. Multiple regression analysis found that gestational age at childbirth was negatively associated with diethylphosphate (DEP) levels (β = -0.073; 95% CI, -0.121, -0.024). Apgar score at 1 and 5 min after birth were negatively associated with diethyldithiophosphate (DEDTP) levels (β = -0.036; 95% CI, -0.069, -0.003; and β = -0.034, 95% CI, -0.057, -0.011, respectively). In addition, DEDTP levels were negatively associated with maternal age (β = -0.181; 95% CI, -0.339, -0.023), and dimethylphosphate (DMP) levels were positively associated with frequency of agricultural work during pregnancy (β = 31.554; 95% CI, 0.194, 62.914). Our results indicate that prenatal OP exposure can cause adverse birth outcomes in babies. Therefore, it is necessary to develop an effective strategy for reducing prenatal exposure to OP pesticides.

Pregnancy exposure to organophosphate esters and the risk of attention-deficit hyperactivity disorder in the Norwegian mother, father and child cohort study

BACKGROUND

Organophosphate esters (OPEs) are a class of flame retardants in common use. OPEs can easily leach from materials, resulting in human exposure. Increasing concentrations have been reported in human populations over the past decade. Recent studies have linked prenatal OPE exposure to hyperactivity and attention problems in children. Such behaviors are often found among children with attention-deficit hyperactivity disorder (ADHD), however, no study has investigated OPEs in relation to clinically assessed ADHD.

OBJECTIVE

To evaluate prenatal exposure to OPEs as risk factors for clinically assessed ADHD using a case-cohort study nested within the Norwegian Mother, Father, and Child Cohort Study (MoBa).

METHODS

We included in the case group 295 ADHD cases obtained via linkage with the Norwegian Patient Registry, and the sub-cohort group 555 children sampled at baseline, irrespective of their ADHD case status. Prenatal concentrations of OPE metabolites were measured in maternal urine collected at 17 weeks of gestation, and included diphenyl phosphate (DPHP), di-n-butyl phosphate (DNBP), bis(2-butoxyethyl) hydrogen phosphate (BBOEP), and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP). We estimated risk ratios and the corresponding 95% confidence intervals [95% CI] using logistic regression, adjusting for season of urine collection, child sex, birth year, and maternal depression, education, and sum of urinary di(2-ethylhexyl) phthalate metabolites (∑DEHP) concentration during pregnancy. To assess the overall impact of simultaneously decreasing exposure to all chemical constituents of an OPE-phthalate mixture, quantile based g-computation was implemented. The mixture constituents included OPE and phthalate metabolites commonly detected in our study. In all models, we considered effect measure modification by child sex and polymorphisms in genes encoding paraoxonase 1 (PON1) and cytochrome P450 (P450) enzymes. Mediation analysis was conducted using thyroid function biomarkers estimated from maternal blood collected at 17 weeks of gestation.

RESULTS

DPHP was detected in nearly all samples (97.2%), with a higher geometric mean among the case group (0.70 µg/L) as compared to the sub-cohort (0.52 µg/L). DNBP was commonly detected as well (93.8%), while BBOEP (52.9%) and BDCIPP (22.9%) were detected less frequently. A higher risk of ADHD was observed in children with greater than median exposure to DPHP during pregnancy (risk ratio: 1.38 [95% CI: 0.96, 1.99]), which was slightly higher among girls (2.04 [1.03, 4.02]) and children of mothers with PON1 Q192R genotype QR (1.69 [0.89, 3.19]) or PON1 Q192R genotype RR (4.59 [1.38, 15.29]). The relationship between DPHP and ADHD (total risk ratio: 1.34 [0.90, 2.02]) was partially mediated through total triiodothyronine to total thyroxine ratio (natural direct effect: 1.29 [0.87, 1.94]; natural indirect effect: 1.04 [1.00, 1.10]; 12.48% mediated). We also observed an elevated risk of ADHD in relation to BDCIPP detection during pregnancy (1.50 [0.98, 2.28]). We did not observe notable differences in ADHD by DNBP (0.88 [0.62, 1.26]) or BBOEP (1.03 [0.73, 1.46]) during pregnancy. Simultaneously decreasing all constituents of common-detect OPE-phthalate mixture, specifically DPHP, DNBP, and 6 phthalate metabolites, by a quartile resulted in an ADHD risk ratio of 0.68 [0.64, 0.72].

CONCLUSION

Prenatal exposure to DPHP and BDCIPP may increase the risk of ADHD. For DPHP, we observed potential modification by child sex and maternal PON1 Q192R genotype and partial mediation through maternal thyroid hormone imbalance at 17 weeks gestation.

Quantification of Nonpersistent Pesticides in Small Volumes of Human Breast Milk with Ultrahigh Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry

Existing methods for the analysis of pesticides in human breast milk involve multiple extraction steps requiring large sample and solvent volumes, which can be a major obstacle in large epidemiologic studies. Here, we developed a simple, low-volume method for extracting organophosphates, pyrethroids, carbamates, atrazine, and imidacloprid from 100 to 200 μL of human breast milk. Multiple extraction protocols were tested including microwave-assisted acid/base digestion and double-solvent extraction with 2 or 20 mL of 2:1 (v/v) dichloromethane/hexane, with or without subsequent solid-phase extraction (SPE) cleanup. Samples were analyzed by liquid chromatography tandem mass spectrometry. Analyte recoveries and reproducibility were highest when 100-200 μL of milk were extracted with 2 mL of dichloromethane/hexane without subsequent SPE steps. Analysis of 79 breast milk samples using this method revealed the presence of carbamates, organophosphates, pyrethroids, and imidacloprid at detection frequencies of 79-96, 53-90, 1-7, and 61%, respectively. This study demonstrates the feasibility of a simple low-volume extraction method for measuring pesticides in human breast milk.

Organophosphate pesticide exposure during pregnancy and childhood and onset of juvenile delinquency by age 16 years: The CHAMACOS cohort

BACKGROUND

Though prenatal organophosphate pesticide (OP) exposure has been associated with lower intellectual quotient and behavioral disorders in childhood, factors related to later delinquency, no research has directly evaluated the impact of OPs on delinquency.

OBJECTIVE

To evaluate the association between prenatal and childhood OP exposure and juvenile delinquency in Mexican-American youth in the Center for Health Assessment of Mothers and Children of Salinas (CHAMACOS).

METHODS

We measured dialkyl phosphate (DAPs) urinary metabolites of OPs in two prenatal maternal samples and in five child samples collected between six months and five years of age. Youth completed delinquency questionnaires at 16 years. We examined associations of prenatal and childhood DAPs with several delinquency outcomes (n = 313) using survival and generalized linear models.

RESULTS

Almost 60% of youth reported delinquent acts (mostly minor), and 8% reported a police arrest. We observed largely null results of prenatal or childhood DAP concentrations and delinquency outcomes, with some isolated associations. A ten-fold increase in maternal dimethylphosphate (DM) concentrations measured after 20 weeks gestation was associated with an earlier age of first delinquent act (Hazard Ratio = 1.38, 95% CI: 1.01, 1.88) and an increased Odds Ratio (OR) of having committed 1-3 or ≥4 delinquent acts, compared to the no delinquency reference group (OR = 1.77, 95% CI: 1.01-3.08 and 2.17, 95% CI: 1.13-4.17, respectively). Higher childhood diethylphosphate (DE) concentrations were associated with a later age of first delinquent act (HR: 0.67; 95% CI: 0.46-0.97).

DISCUSSION

We did not find strong evidence of association between prenatal or childhood OP exposure and juvenile delinquency in the present cohort. There is an increasing literature that relates OP exposure to neurobehavioral impairments in childhood, and there is a need to understand long-term potential neurodevelopmental effects of early-life OP exposure.

Chlorpyrifos and other pesticide exposure and suspected developmental delay in children aged under 5 years: a case-control study in Phitsanulok, Thailand

Background: Developmental delay among children under 5 years of age is a serious global public health problem and much research has been carried out to find potential causes. Pesticides - especially organophosphates - are suspected to be one of the main causes of the problem.  This study aimed to investigate the association between pesticide use by the mother during pregnancy and preschool children development using a case-control study. Methods: Data on prenatal and postnatal pesticide exposure of 442 children with suspected developmental delay, and 413 controls with normal development were included for analysis. The children were matched for gender, age, and residency. Data on pesticide exposure were collected via interview with the mother, and data on pregnancy outcomes abstracted from hospital records.   Results: Chlorpyrifos exposure significantly increased the risk of developmental delay with an odds ratio (OR) of 3.71 (95% CI 1.03-13.36) for ever use of the pesticide, and an OR of 5.92 (95% CI 1.01-34.68) for postnatal exposure (p <0.05). Some other pesticides also had a positive association with developmental delay but none were statistically significant (p <0.05). Those pesticides were insecticide, fungicide, herbicide, and molluscicide. Individual pesticides with a positive association were glyphosate, paraquat, butachlor, methyl parathion (pholidon), savin, methomyl, endosulfan, carbosulfan, methamidophos, monochrotofos, mancozeb, and bordeaumixture. Conclusions: This case-control study found that chlorpyrifos and some other pesticides exposure during pregnancy were positively associated with developmental delay in children aged under 5 years. Further research should be conducted to better understand this potential effects of pesticides on child neurodevelopment, and the public - especially those who plan to have families - should be informed.

Translational outcomes relevant to neurodevelopmental disorders following early life exposure of rats to chlorpyrifos

BACKGROUND

Neurodevelopmental disorders (NDDs), including intellectual disability, attention deficit hyperactivity disorder (ADHD), and autism spectrum disorder (ASD), are pervasive, lifelong disorders for which pharmacological interventions are not readily available. Substantial increases in the prevalence of NDDs over a relatively short period may not be attributed solely to genetic factors and/or improved diagnostic criteria. There is now a consensus that multiple genetic loci combined with environmental risk factors during critical periods of neurodevelopment influence NDD susceptibility and symptom severity. Organophosphorus (OP) pesticides have been identified as potential environmental risk factors. Epidemiological studies suggest that children exposed prenatally to the OP pesticide chlorpyrifos (CPF) have significant mental and motor delays and strong positive associations for the development of a clinical diagnosis of intellectual delay or disability, ADHD, or ASD.

METHODS

We tested the hypothesis that developmental CPF exposure impairs behavior relevant to NDD phenotypes (i.e., deficits in social communication and repetitive, restricted behavior). Male and female rat pups were exposed to CPF at 0.1, 0.3, or 1.0 mg/kg (s.c.) from postnatal days 1-4.

RESULTS

These CPF doses did not significantly inhibit acetylcholinesterase activity in the blood or brain but significantly impaired pup ultrasonic vocalizations (USV) in both sexes. Social communication in juveniles via positive affiliative 50-kHz USV playback was absent in females exposed to CPF at 0.3 mg/kg and 1.0 mg/kg. In contrast, this CPF exposure paradigm had no significant effect on gross locomotor abilities or contextual and cued fear memory. Ex vivo magnetic resonance imaging largely found no differences between the CPF-exposed rats and the corresponding vehicle controls using strict false discovery correction; however, there were interesting trends in females in the 0.3 mg/kg dose group.

CONCLUSIONS

This work generated and characterized a rat model of developmental CPF exposure that exhibits adverse behavioral phenotypes resulting from perinatal exposures at levels that did not significantly inhibit acetylcholinesterase activity in the brain or blood. These data suggest that current regulations regarding safe levels of CPF need to be reconsidered.

Synthetic Pesticides and Health in Vulnerable Populations: Agricultural Workers

PURPOSE OF REVIEW

This review aims to summarize epidemiological literature published between May 15, 2018, and May 14, 2019, that examines the relationship between exposure to synthetic pesticides and health of agricultural workers.

RECENT FINDINGS

Current research suggests that exposure to synthetic pesticides may be associated with adverse health outcomes. Agricultural workers represent a potentially vulnerable population, due to a combination of unique social and cultural risk factors as well as exposure to hazards inherent in agricultural work. Pesticide exposure among agricultural workers has been linked to certain cancers, DNA damage, oxidative stress, neurological disorders, and respiratory, metabolic, and thyroid effects. This review describes literature suggesting that agricultural workers exposed to synthetic pesticides are at an increased risk of certain cancers and neurological disorders. Recent research on respiratory effects is sparse, and more research is warranted regarding DNA damage, oxidative stress, metabolic outcomes, and thyroid effects.

A framework for assessing the impact of chemical exposures on neurodevelopment in ECHO: Opportunities and challenges

The Environmental influences on Child Health Outcomes (ECHO) Program is a research initiative funded by the National Institutes of Health that capitalizes on existing cohort studies to investigate the impact of early life environmental factors on child health and development from infancy through adolescence. In the initial stage of the program, extant data from 70 existing cohort studies are being uploaded to a database that will be publicly available to researchers. This new database will represent an unprecedented opportunity for researchers to combine data across existing cohorts to address associations between prenatal chemical exposures and child neurodevelopment. Data elements collected by ECHO cohorts were determined via a series of surveys administered by the ECHO Data Analysis Center. The most common chemical classes quantified in multiple cohorts include organophosphate pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, environmental phenols (including bisphenol A), phthalates, and metals. For each of these chemicals, at least four ECHO cohorts also collected behavioral data during infancy/early childhood using the Child Behavior Checklist. For these chemicals and this neurodevelopmental assessment (as an example), existing data from multiple ECHO cohorts could be pooled to address research questions requiring larger sample sizes than previously available. In addition to summarizing the data that will be available, the article also describes some of the challenges inherent in combining existing data across cohorts, as well as the gaps that could be filled by the additional data collection in the ECHO Program going forward.

Prenatal maternal organophosphorus pesticide exposures, paraoxonase 1, and childhood adiposity in the Mount Sinai Children's Environmental Health Study

BACKGROUND

Animal studies suggest that organophosphorus pesticides (OPs) may be environmental obesogens. While prenatal OP exposures have been associated with altered infant glucose metabolism, associations with pediatric adiposity remain unknown.

METHODS

We summed concentrations of three dimethylphosphate (∑DMP) and three diethylphosphate (∑DEP) metabolites of OPs measured in third trimester spot urine samples collected from pregnant women enrolled in New York City, 1998-2002. We measured percent fat mass using bio-electrical impedance analysis and calculated age- and sex-standardized body mass index (BMI) z-scores from anthropometric measurements collected at approximately 4, 6, and 7-9 years of age (166 children, 333 observations). We assessed covariate-adjusted associations of OPs with repeated adiposity measures using linear mixed models and evaluated effect measure modification (EMM) by sex and paroxonase (PON) 1 -108C/T and Q192R polymorphisms measured in maternal peripheral blood samples.

RESULTS

The geometric mean urinary concentration of ∑DMP metabolites (29.9 nmol/L, IQR: 105.2 nmol/L) was higher than ∑DEP metabolites (8.8 nmol/L, IQR: 31.2 nmol/L). Adjusted associations were null, with differences in fat mass per 10-fold increase in prenatal ∑DMP and ∑DEP concentrations of 0.7% (95% CI: -0.6, 2.0) and 0.8% (95% CI: -0.4, 2.0), respectively. Maternal PON1-108C/T polymorphisms modified relationships of prenatal ∑DMP with percent fat mass (EMM p-value = 0.18) and ∑DEP with BMI z-scores (EMM p-value = 0.12). For example, ∑DMP was modestly associated with increased percent fat mass among children of mothers with the at-risk CT or TT genotype (β = 1.2%, 95% CI: -0.6, 3.0) but not among those whose mothers had the CC genotype (β = -0.4%, 95% CI: -2.4, 1.5). Associations were not modified by sex or maternal PON1 Q192R polymorphisms.

CONCLUSIONS

We observed little evidence of a relationship between prenatal OP exposures and child adiposity, although there was some suggestion of increased risk among offspring of mothers who were slow OP metabolizers. Larger studies are warranted to further evaluate possible associations of prenatal OP exposures with child adiposity and differences by maternal PON1 genotype, which regulates OP metabolism and may increase susceptibility to exposure.

Residential proximity to greenhouse crops and pesticide exposure (via acetylcholinesterase activity) assessed from childhood through adolescence

BACKGROUND

Off-target drift of pesticides from farms increases the risk of pesticide exposure of people living nearby. Cholinesterase inhibitors (i.e. organophosphates and carbamates) are frequently used in agriculture and inhibit acetylcholinesterase (AChE) activity. Greenhouse agriculture is an important production method, but it is unknown how far pesticide drift from greenhouses can extend and expose people living nearby.

METHODS

This study included 1156 observations from 3 exams (2008, Apr, 2016 and Jul-Oct 2016) of 623 children aged 4-to-17 years living in agricultural communities in Ecuador. AChE, a physiological marker of cholinesterase inhibitor exposure, was measured in blood. Geographic positioning of greenhouses and homes were obtained using GPS receivers and satellite imagery. Distances between homes and the nearest greenhouse edge, and areas of greenhouse crops within various buffer zones around homes were calculated. Repeated-measures regression adjusted for hemoglobin and other covariates estimated change in AChE relative to distance from greenhouses.

RESULTS

The pooled mean (SD) of AChE activity was 3.58 U/mL (0.60). The median (25th-75th %tile) residential distance to crops was 334 m (123, 648) and crop area within 500 m of homes (non-zero values only) was 18,482 m2 (7115, 61,841). Residential proximity to greenhouse crops was associated with lower AChE activity among children living within 275 m of crops (AChE difference per 100 m of proximity [95% CI] = -0.10 U/mL [-0.20, -0.006]). Lower AChE activity was associated with greater crop area within 500 m of homes (AChE difference per 1000 m2 [95% CI] = -0.026 U/mL [-0.040, -0.012]) and especially within 150 m (-0.037 U/mL [-0.065, -0.007]).

CONCLUSIONS

Residential proximity to floricultural greenhouses, especially within 275 m, was associated with lower AChE activity among children, reflecting greater cholinesterase inhibitor exposure from pesticide drift. Analyses of residential proximity and crop areas near homes yielded complementary findings. Mitigation of off-target drift of pesticides from crops onto nearby homes is recommended.

Predictors of Urinary Pyrethroid and Organophosphate Compound Concentrations among Healthy Pregnant Women in New York

Our study aimed to investigate dietary and non-dietary predictors of exposure to pyrethroids, organophosphates pesticides and 2,4-D herbicide in two cohorts of pregnant women in New York City: 153 women from the Thyroid Disruption and Infant Development (TDID) cohort and 121 from the Sibling/Hermanos Cohort(S/H). Baseline data on predictors were collected from the women at time of recruitment. We used three different modeling strategies to address missing data due to biomarker values below the limit of detection (<LOD): (1) logistic regression models with biomarkers categorized as (<median, ≥median); (2) linear regression models, imputing the <LOD values with (LOD/√2); (3) regression models, considering <LOD values as left-censored. Generally, all three models identified similar predictors of exposure. We found that ethnicity, higher income and education predicted higher concentrations of most of the biomarkers in both cohorts. Mothers who consumed processed meat in the TDID cohort, and broiled, barbequed food or burgers in the S/H cohort, tended to have lower concentrations of organophosphates and 2,4-D. The choice of modeling led to a few different predictors identified, and the selection of modeling strategy should be based on the study question.

Gestational exposures to organophosphorus insecticides: From acute poisoning to developmental neurotoxicity

For over three-quarters of a century, organophosphorus (OP) insecticides have been ubiquitously used in agricultural, residential, and commercial settings and in public health programs to mitigate insect-borne diseases. Their broad-spectrum insecticidal effectiveness is accounted for by the irreversible inhibition of acetylcholinesterase (AChE), the enzyme that catalyzes acetylcholine (ACh) hydrolysis, in the nervous system of insects. However, because AChE is evolutionarily conserved, OP insecticides are also toxic to mammals, including humans, and acute OP intoxication remains a major public health concern in countries where OP insecticide usage is poorly regulated. Environmental exposures to OP levels that are generally too low to cause marked inhibition of AChE and to trigger acute signs of intoxication, on the other hand, represent an insidious public health issue worldwide. Gestational exposures to OP insecticides are particularly concerning because of the exquisite sensitivity of the developing brain to these insecticides. The present article overviews and discusses: (i) the health effects and therapeutic management of acute OP poisoning during pregnancy, (ii) epidemiological studies examining associations between environmental OP exposures during gestation and health outcomes of offspring, (iii) preclinical evidence that OP insecticides are developmental neurotoxicants, and (iv) potential mechanisms underlying the developmental neurotoxicity of OP insecticides. Understanding how gestational exposures to different levels of OP insecticides affect pregnancy and childhood development is critical to guiding implementation of preventive measures and direct research aimed at identifying effective therapeutic interventions that can limit the negative impact of these exposures on public health.

Revisiting the Tropospheric OH-Initiated Unimolecular Decomposition of Chlorpyrifos and Chlorpyrifos-Methyl: A Theoretical Perspective

Based on density functional theory (DFT) electronic structure calculations with dispersion correction, we propose new reaction pathways in which no extra reaction step is necessary to account for the formation of 3,5,6-trichloro-2-pyridynol (TCP) within the process of tropospheric OH-initiated unimolecular decomposition of chlorpyrifos (CLP) and chlorpyrifos-methyl (CLPM). Chlorpyrifos and its analogous compound are among the most used organophosphorus pesticides worldwide, and their unimolecular decomposition in the troposphere is a dominant process of removal in the gas phase. The reaction pathways that we put forward have turned out to be the most exergonic ones among the three possible routes for the attack of the hydroxyl radical to the thiophosphoryl (P═S) bond of both CLP and CLPM. The results showed that the reaction is thermodynamically controlled with the formation of P-bonded adducts via a six-membered ring. The unimolecular decomposition of such reactive intermediates takes place with small energy barriers (less than 3 kcal mol^-1) and is distinguished by hydrogen transfer to the nitrogen atom of the aromatic ring, resulting in the formation of 3,5,6-trichloro-2-pyridinol (TCP) and dialkyl phosphate radical (DAP·) product complexes in a single step.

Pesticides in the urban environment: A potential threat that knocks at the door

Pesticides play a pivotal role in controlling pests and disease infestations not only in urban agriculture but also in non-agricultural settings. Several pesticides like herbicides, insecticides, fungicides, rodenticides, etc. are applied unintentionally at higher concentrations even in small urban areas such as lawns, gardens and impermeable surfaces. Consequent to their indiscriminate use, both extensively and intensively, in the urban areas, contamination of pesticides poses a serious threat to the environment, living organisms and food safety. Although the fate and ecological effects of pesticides and their residues have been thoroughly understood in agricultural soils, information available in the literature on the impact of these contaminants in the urban environment is very limited and fragmentary. In fact, the fate and behaviour of pesticide residues in the urban environment are distinct from those in other ecosystems since the soils in urban areas greatly vary in their physico-chemical properties. Development of sustainable and eco-friendly approaches for remediation of even urban soils contaminated with pesticides is therefore greatly warranted. Thus, the present critical review is the first single source that provides updated knowledge on the sources, nature and extent of pesticide pollution in the urban environment, and the ecological and human health effects of pesticides and their residues. The potential of nano-encapsulation of pesticides for their application in urban settings has also been discussed.

A Pilot Study Evaluating Organochlorine and Organophosphate Pesticide Exposure in Children and Adolescents of Mexican Descent Residing in Hidalgo County, Texas

Children and adolescents of Mexican descent residing in Hidalgo County (TX) were evaluated for exposure to organochlorine (OC) and organophosphate (OP) pesticides. A convenience sample of 60 participants enrolled in our pilot study. The lipid-adjusted serum concentrations of nine OC metabolites and creatinine-adjusted urinary concentrations of six OP metabolites were measured and compared with data from the Centers for Disease Control and Prevention's Fourth Report on Human Exposure to Environmental Chemicals. Descriptive statistics were used to summarize the concentration levels for each metabolite. Study participants were aged 5-18 years. For most of the OC and OP metabolites, our findings showed that participants had concentration levels within the distributional range of the national data. However, notable outlying levels (greater than the 95th percentile in the Fourth Report) were identified for the following OC metabolites: gamma-hexachlorocyclohexane, p,p'-dichlorodiphenyldichloroethene, and p,p'-dichlorodiphenyltrichloroethane. Among the children aged 5-11 years, one child had an outlying value for the OP metabolite: dimethylphosphate. Our findings on the levels of OC and OP pesticide exposure enhances the credibility of national estimates, and can serve as baselines for children and adolescents of Mexican descent residing in Lower Rio Grande Valley. Furthermore, our study contributes to the lacunae of knowledge regarding environmental exposures and presses further investigation of outlying OC and OP exposure levels.

Organophosphate pesticide metabolite concentrations in urine during pregnancy and offspring attention-deficit hyperactivity disorder and autistic traits

BACKGROUND

Prenatal exposure to organophosphate (OP) pesticides has been associated with altered neuronal cell development and behavioral changes in animal offspring. However, the few studies investigating the association between prenatal OP pesticide exposure and neurodevelopmental outcomes such as Attention-Deficit Hyperactivity Disorder (ADHD) and autistic traits in children produced mixed findings.

OBJECTIVE

The objective of the present study was to examine whether maternal urinary concentrations of OP pesticide metabolites are associated with ADHD and autistic traits in children participating in the Generation R Study, a population-based birth cohort from Rotterdam, the Netherlands.

METHOD

Maternal concentrations of 6 dialkylphosphates (DAPs) were measured using gas chromatography coupled with tandem mass spectrometry in urine samples collected at <18 weeks, 18-25 weeks, and > 25 weeks of gestation in 784 mother-child pairs. DAP metabolite concentrations were expressed as molar concentrations divided by creatinine levels and log10 transformed. ADHD traits were measured at ages 3, 6, and 10 years using the Child Behavior Checklist (CBCL) (n = 781) and autistic traits were measured at age 6 years using the Social Responsiveness Scale (SRS) (n = 622). First, regression models were fit for the averaged prenatal exposure across pregnancy. Second, we investigated associations for each collection phase separately, and applied a mutually adjusted model in which the effect of prenatal DAP concentrations from each time period on ADHD and autistic traits were jointly estimated. All associations were adjusted for relevant confounders.

RESULTS

Median DAP metabolite concentration was 309 nmol/g creatinine at <18 weeks, 316 nmol/g creatinine at 18-25 weeks, and 308 nmol/g creatinine at >25 weeks of gestation. Overall, DAP metabolite concentrations were not associated with ADHD traits. For instance, a log10 increase in averaged total DAP concentrations across gestation was not associated with a lower ADHD score (-0.03 per SD 95 CI: -0.28 to 0.23). Similarly, no associations between maternal DAP concentrations and autistic traits were detected.

CONCLUSIONS

In this study of maternal urinary DAP metabolite concentrations during pregnancy, we did not observe associations with ADHD and autistic traits in children. These are important null observations because of the relatively high background DAP concentrations across pregnancy, the relatively large sample size, and the 10-year follow-up of the offspring. Given the measurement error inherent in our OP pesticide exposure biomarkers, future studies using more urine samples are needed to accurately measure OP pesticide exposure over pregnancy in relation to ADHD and autistic traits.

An educational intervention on the risk perception of pesticides exposure and organophosphate metabolites urinary concentrations in rural school children in Maule Region, Chile

BACKGROUND

Organophosphate (OP) pesticides can be hazardous to human health if not applied with appropriate precautions. There is evidence in the Maule region of Chile that rural schoolchildren are exposed to OP pesticides.

OBJECTIVE

To evaluate the effectiveness of an educational intervention on OP exposure and understanding of pesticides and their hazards (risk perception) in two school communities in the Maule Region of Chile during 2016.

METHOD

We conducted a quasi-experimental study about the effects on OP pesticide exposure of a community outreach and education program (COEP) administered in four 2-h sessions that's included hands-on activities among 48 schoolchildren from two rural schools. The intervention was directed to groups of parents and school-children separately, and aimed to educate them about the risks of exposure to pesticides and their effects on health. We measured 3,5,6-trichloro-2-pyridinol (TCPy), 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPY), malathion dicarboxylic acid (MDA), p-nitrophenol (PNP), specific urinary metabolites of the OP pesticides chlorpyrifos, diazinon, malathion and parathion, respectively, as well as the non-specific diethylakylphosphates (DEAPs) and dimethylalkylphosphates (DMAPs) in 192 urine samples of schoolchildren collected before and after the intervention. The risk perception of school children and their parents was also assessed through a questionnaire before and after the intervention. Generalized Estimated Equations were used to account for each child's repeated measures during four sessions, two in September 2016 (pre-intervention) and two in November 2016 (post-intervention).

RESULTS

The intervention level had significant effect on the risk perception of adults and children, which increased after the intervention. However, the intervention was not associated with reduced of urinary metabolites levels, with no significant differences between the pre and post measures. The detection frequencies were 1.1% (MDA), 71.4% (TCPy), 43.3% (IMPY), 98.96% (PNP), and 100% (DEAPs and DMAPs). Higher DEAPs urine concentrations were associated with eating more fruit at school (p = 0.03), a younger age (p = 0.03), and being male (p = 0.01). DMAPs showed no associations with potential predictor variables (e.g. OPs applied at home, fruit consumption at school, among others). Higher TCPy was associated with attending a school closer to farms (p = 0.04) and living in a home closer to farm fields (p = 0.01); higher PNP was marginally associated with children younger age (p = 0.035).

CONCLUSION

Environmental exposure to OP pesticides was unchanged even after behavior changes. It is possible that a longer time period is needed to observe changes in both behavior and urinary metabolites. The levels of DEP and DMP metabolites found here are above the reference population of the US, and our findings indicate exposure to a wide variety of OP pesticides. Given that individual-level interventions were not associated with lower exposures, efforts to reduce exposure must occur upstream and require stricter regulation and control of pesticide use by government agencies.

Effects of prenatal and postnatal exposure to organophosphate pesticides on child neurodevelopment in different age groups: a systematic review

Exposure to pesticides is a major factor in the cause of dysfunction in the nervous system and neurodevelopment disorders in children at critical periods of great vulnerability. The aim of this study was to review scientific evidence published on neurodevelopmental effects of prenatal and postnatal exposure to organophosphate pesticides (OPs) in different stages, including neonates, infants, toddlers, preschool children, and school-age children. Full-text articles published in PubMed, Scopus, and ISI databases between 1973 and 2019 were reviewed and the scientific evidence was evaluated. Results: Fifty studies were eligible for inclusion in this quantitative synthesis. Fifteen of these papers evaluated the effects on neonates and infants, 18 on the effects on toddlers and preschool children, and 24 the effects on school-age children. Considerable evidence suggests that prenatal exposure to OPs contributes to child neurodevelopment disorders in all stages, whereas data about the effects of postnatal exposure are limited. Therefore, the available evidence supports the theory that sensitive time-windows occur prenatally rather than postnatally. Although 45 out of the total 50 selected articles found an association between OP exposure and child neurodevelopment, some of the evidence is controversial. A standardized methodology is needed to enable the comparison of the results in several studies, and further research studies are needed to warrant firmer conclusions. A systematic review of this evidence should be performed continuously to update the state of knowledge regarding neurodevelopmental effects associated with OP exposure.

Impaired innate and conditioned social behavior in adult C57Bl6/J mice prenatally exposed to chlorpyrifos

Background

Signs of pervasive developmental disorder and social deficits were reported in toddlers and children whose mothers were exposed to organophosphate pesticides during pregnancy. Deficits in social preference were reported in adult male mice exposed to chlorpyrifos on gestational days 12–15. This study aimed (a) to test the hypothesis that adult female and male mice that were exposed prenatally to subtoxic doses of chlorpyrifos would be impaired in social behavior and (b) to determine if prenatal chlorpyrifos altered the expression of transcripts for oxytocin in the hypothalamus. Pregnant mice were treated by gavage with corn oil vehicle or 2.5 mg/kg or 5 mg/kg of CPF on gestational days 12–15. Social preference, social and non-social conditioned place preference tasks were tested in adults. Expression of oxytocin transcripts in hypothalamus was measured by qPCR.

Results

Chlorpyrifos (5 mg/kg on GD 12–15) reduced the innate preference for a conspecific in a dose and sex dependent manner. Adult males exposed prenatally to 5 mg/kg CPF showed a reduction in social preference. Socially conditioned place preference was impaired in offspring of dams treated with either dose of CPF. Non-social appetitive place conditioning was impaired in offspring of dams exposed to 2.5 mg/kg, but not to 5 mg/kg chlorpyrifos. Prenatal chlorpyrifos treatment did not alter the expression of the oxytocin mRNA in the hypothalamus, although expression was significantly lower in females.

Conclusions

Prenatal chlorpyrifos induced innate and learned social deficits and non-specific conditioning deficits in adult mice in a sex-dependent manner. Males showed specific social deficits following the higher dose whereas both males and females showed a more generalized conditioning deficit following the intermediate dose.

Intra-individual variations of organophosphate pesticide metabolite concentrations in repeatedly collected urine samples from pregnant women in Japan

BACKGROUND

Low-dose exposure to organophosphate (OP) insecticides during pregnancy may adversely affect neurodevelopment in children. To evaluate the OP exposure levels, single urine sampling is commonly adopted to measure the levels of dialkylphosphates (DAPs), common OP metabolites. However, the inter-day variations of urinary DAP concentrations within subjects are supposed to be large due to the short biological half-lives of the metabolites, and it is thus considered difficult to accurately assess OP exposure during pregnancy with single sampling. This study aimed to assess intra-individual variations of DAP concentrations and the reproducibility of the exposure dose categorization of OPs according to DAP concentration ranges in pregnant women in Japan.

METHODS

Urine samples were collected from 62 non-smoking pregnant women (12-22 weeks of gestation) living in Aichi Prefecture, Japan. First morning void (FMV) and spot urine samples taken between lunch and dinner on the same day were collected on five different days during 2 weeks. The concentrations of DAP and creatinine in urine samples were measured using an ultra performance liquid chromatography with tandem mass spectrometry. Creatinine-adjusted and unadjusted concentrations were used for the intraclass correlation coefficient (ICC) calculations and surrogate category analyses.

RESULTS

For all DAP metabolites, the creatinine-adjusted single ICCs exceeded 0.4, indicating moderate reliability. Overall, ICCs of spot urine samples taken in the afternoon were better than those taken as FMV. Surrogate category analyses showed that participants were categorized accurately into four exposure dose groups according to the quartile points.

CONCLUSION

This study indicated that a single urine sample taken in the afternoon may be useful in assessing OP exposure as long as the exposure is categorized into quartiles when conducting epidemiological studies in early to mid-pregnant women in Japan.

Differential occurrence, profiles and uptake of dust contaminants in the Barcelona urban area

Dust is a complex but increasingly used matrix to assess human exposure to organic contaminants both in indoor and outdoor environments. Knowledge concerning the effects of organic pollution towards health outcome is crucial. This study is aimed to determine the presence of legacy compounds (DDTs and polychlorinated biphenyls, PCBs), compounds used in recent times (organophosphorous flame retardants, organophosphorous pesticides, BPA, phthalates and alkylphenols) and compounds originated from combustion processes (polycyclic aromatic hydrocarbons, PAHs) as well as nicotine in indoor environments along the metropolitan area of Barcelona. Monitored sites include public areas with high turnout (high schools, museums samples) and libraries and private spaces (houses and cars). Almost all compounds (57 over the 59 targeted) were found in each dust sample and libraries and schools were the most contaminated, with concentrations of ∑phthalates and ∑OPFRs up to 15 and 10 mg g^-1, respectively. One-way ANOVA tests, Tukey contrasts and principal component analysis (PCA) revealed that sampling place influenced the observed contamination profiles and public and private environments were clearly differentiated. Finally, based on the concentrations detected, a deterministic calculation was performed to estimate the total daily intakes of each compound via dust. This information was used to evaluate the human exposure for toddlers, teenagers and adult workers. Consistently, the highest concentrations coming from plasticisers and flame retardants gave the major exposure rates. As expected, toddlers were the most affected group followed by museum and library workers, although the levels were below the reference doses.

Children's low-level pesticide exposure and associations with autism and ADHD: a review

Pesticides are chemicals that are designed specifically for the purpose of killing or suppressing another living organism. Human toxicity is possible with any pesticide, and a growing body of literature has investigated possible associations with neurodevelopmental disorders. Attention deficit disorder with or without hyperactivity (ADHD) and autism spectrum disorder (ASD) are two of these specific disorders that have garnered particular interest. Exposure to toxic chemicals during critical windows of brain development is a biologically plausible mechanism. This review describes the basic laboratory science including controlled pesticide dosing experiments in animals that supports a mechanistic relationship in the development of ADHD and/or ASD. Epidemiological relationships are also described for low-level pesticide exposure and ADHD and/or ASD. The available evidence supports the hypothesis that pesticide exposure at levels that do not cause acute toxicity may be among the multifactorial causes of ADHD and ASD, though further study is needed, especially for some of the newer pesticides.

Organophosphate Pesticide Metabolite Concentrations in Urine during Pregnancy and Offspring Nonverbal IQ at Age 6 Years

BACKGROUND

Susceptibility to organophosphate (OP) pesticide neurotoxicity may be greatest during the prenatal period; however, previous studies have produced mixed findings concerning in utero OP pesticide exposure and child cognition.

OBJECTIVES

Our objective was to determine whether maternal urinary concentrations of OP pesticide metabolites are inversely associated with child nonverbal IQ at 6 y of age and to examine potential effect measure modification by the PON1 gene.

METHODS

Data came from 708 mother–child pairs participating in the Generation R Study. Maternal urine concentrations of six dialkylphosphates (DAPs), collected at [Formula: see text], 18–25, and [Formula: see text] of gestation, were determined. Child nonverbal IQ was measured at 6 y of age using the Mosaics and Categories subtests from the Snijders-Oomen Nonverbal Intelligence Test-Revised. PON1 was determined in cord blood for 474 infants. Multiple linear regression models were fit to estimate the DAP-IQ associations and PON1 interactions.

RESULTS

Overall, associations between child nonverbal IQ and maternal DAP concentrations were small and imprecise, and these associations were inconsistent across urine sampling periods. Howover, for a 10-fold difference in total DAP concentration for the [Formula: see text] of gestation samples, adjusted child nonverbal IQ was 3.9 points lower (95% CI: [Formula: see text], [Formula: see text]). Heterogeneity in the DAP–IQ association by PON1 gene allele status was not observed ([Formula: see text]).

CONCLUSIONS

Consistent evidence of an association between higher maternal urinary DAP concentrations and lower child IQ scores at 6 y of age was not observed. There was some evidence for an inverse relation of child nonverbal IQ and late pregnancy urinary DAPs, but the estimated association was imprecise. https://doi.org/10.1289/EHP3024.

A Bayesian approach to the g-formula

Epidemiologists often wish to estimate quantities that are easy to communicate and correspond to the results of realistic public health interventions. Methods from causal inference can answer these questions. We adopt the language of potential outcomes under Rubin's original Bayesian framework and show that the parametric g-formula is easily amenable to a Bayesian approach. We show that the frequentist properties of the Bayesian g-formula suggest it improves the accuracy of estimates of causal effects in small samples or when data are sparse. We demonstrate an approach to estimate the effect of environmental tobacco smoke on body mass index among children aged 4-9 years who were enrolled in a longitudinal birth cohort in New York, USA. We provide an algorithm and supply SAS and Stan code that can be adopted to implement this computational approach more generally.

Early Life Characteristics and Neurodevelopmental Phenotypes in the Mount Sinai Children's Environmental Health Center

Neurodevelopmental outcomes including behavior, executive functioning, and IQ exhibit complex correlational structures, although they are often treated as independent in etiologic studies. We performed a principal components analysis of the behavioral assessment system for children, the behavior rating inventory of executive functioning, and the Wechsler scales of intelligence in a prospective birth cohort, and estimated associations with early life characteristics. We identified seven factors: (1) impulsivity and externalizing, (2) executive functioning, (3) internalizing, (4) perceptual reasoning, (5) adaptability, (6) processing speed, and (7) verbal intelligence. Prenatal fish consumption, maternal education, preterm birth, and the home environment were important predictors of various neurodevelopmental factors. Although maternal smoking was associated with more adverse externalizing, executive functioning, and adaptive composite scores in our sample, of the orthogonally-rotated factors, smoking was only associated with the impulsivity and externalizing factor ([Formula: see text] - 0.82, 95% CI - 1.42, - 0.23). These differences may be due to correlations among outcomes that were accounted for by using a phenotypic approach. Dimension reduction may improve upon traditional approaches by accounting for correlations among neurodevelopmental traits.

Variability of urinary pesticide metabolite concentrations during pregnancy in the MARBLES Study

BACKGROUND

Variability of short-lived urinary pesticide metabolites during pregnancy raises challenges for exposure assessment.

OBJECTIVES

For urinary metabolite concentrations 3-phenoxybenzoic acid (3-PBA) and 3,5,6-trichloro-2-pyridinol (TCPy), we assessed: (1) temporal variability; (2) variation of two urine specimens within a trimester; (3) reliability for pesticide concentrations from a single urine specimen to classify participants into exposure tertiles; and (4) seasonal or year variations.

METHODS

Pregnant mothers (N = 166) in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) Study provided urine specimens (n = 528). First morning void (FMV), pooled, and 24-h specimens were analyzed for 3-PBA and TCPy. For 9 mothers (n = 88 specimens), each urine specimen was analyzed separately (not pooled) to estimate within- and between-person variance components expressed as intraclass correlation coefficients (ICC). Pesticide concentrations from two specimens within a trimester were also assessed using ICC's. Agreement for exposure classifications was assessed with weighted Cohen's kappa statistics. Longitudinal mixed effect models were used to assess seasonal or year variations.

RESULTS

Urinary pesticide metabolites were detected in ≥ 93% of specimens analyzed. The highest ICC from repeated individual specimens was from specific gravity-corrected FMV specimens for 3-PBA (ICC=0.13). Despite high within-person variability, the median concentrations did not differ across trimesters. Concentrations from pooled specimens had substantial agreement predicting exposure categories for TCPy (K = 0.67, 95% CI (0.59, 0.76)) and moderate agreement for 3-PBA (K = 0.59, 95% CI (0.49, 0.69)). TCPy concentrations significantly decreased from 2007 to 2014.

CONCLUSIONS

Pooled specimens may improve exposure classification and reduce laboratory costs for compounds with short biological half-lives in epidemiological studies.

The link of organophosphorus pesticides with neurodegenerative and neurodevelopmental diseases based on evidence and mechanisms

Organophosphorus (OP) compounds have been known as the most widely used pesticides during the past half century and there have been a huge body of literature regarding their association with human chronic diseases. Neurodegenerative and neurodevelopmental disorders including Alzheimer, Parkinson, amyotrophic lateral sclerosis (ALS), attention deficit hyperactivity disorder (ADHD), and autism are among the afflicting neurological diseases which overshadow human life and their higher risk in relation to OP exposures have been uncovered by epidemiological studies. In addition, experimental studies exploring the underlying mechanisms have provided some evidence for involvement of cholinergic deficit, oxidative stress, neuro-inflammation, and epigenetic modifications as the processes which are common in the toxicity of the OP and pathophysiology of the mentioned diseases. In addition, genetic mutations and polymorphisms of different variants of some genes like paraoxonase have been shown to be implicated in both susceptibility to OPs toxicity and neurological diseases. In this article, we reviewed the epidemiological as well as experimental studies evidencing the association of exposure to OPs and incidence of neurodegenerative and neurodevelopmental diseases.

Associations of prenatal environmental phenol and phthalate biomarkers with respiratory and allergic diseases among children aged 6 and 7 years

BACKGROUND

Prenatal environmental phenol and phthalate exposures may alter immune or inflammatory responses leading to respiratory and allergic disease.

OBJECTIVES

We estimated associations of prenatal environmental phenol and phthalate biomarkers with respiratory and allergic outcomes among children in the Mount Sinai Children's Environmental Health Study.

METHODS

We quantified urinary biomarkers of benzophenone-3, bisphenol A, paradichlorobenzene (as 2,5-dichlorophenol), triclosan, and 10 phthalate metabolites in third trimester maternal samples and assessed asthma, wheeze, and atopic skin conditions via parent questionnaires at ages 6 and 7 years (n = 164 children with 240 observations). We used logistic regression to estimate covariate-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) per standard deviation difference in natural log biomarker concentrations and examined effect measure modification by child's sex.

RESULTS

Associations of prenatal 2,5-dichlorophenol (all outcomes) and bisphenol A (asthma outcomes) were modified by child's sex, with increased odds of outcomes among boys but not girls. Among boys, ORs for asthma diagnosis per standard deviation difference in biomarker concentration were 3.00 (95% CI: 1.36, 6.59) for 2,5-dichlorophenol and 3.04 (95% CI: 1.38, 6.68) for bisphenol A. Wheeze in the past 12 months was inversely associated with low molecular weight phthalate metabolites among girls only (OR: 0.27, 95% CI: 0.13, 0.59) and with benzophenone-3 among all children (OR: 0.65, 95% CI: 0.44, 0.96).

CONCLUSIONS

Prenatal bisphenol A and paradichlorobenzene exposures were associated with pediatric respiratory outcomes among boys. Future studies may shed light on biological mechanisms and potential sexually-dimorphic effects of select phenols and phthalates on respiratory disease development.

Prenatal exposure to organophosphate pesticides and risk of autism spectrum disorders and other non-typical development at 3 years in a high-risk cohort

INTRODUCTION

Organophosphates are widely used pesticides that have been shown to affect child neurodevelopment. Previous studies that explored their potential effects on Autism Spectrum Disorder (ASD) relied either on proxies of external exposure or on questionnaires completed by the parents to identify autism-like behaviors but did not provide a clinical diagnosis of ASD.

AIMS

We studied the associations between prenatal biologic markers for exposure to organophosphate pesticides and the risk of having a child with ASD or other developmental concerns (ODC).

METHOD

We analyzed 203 mother-child pairs of the ongoing MARBLES (Markers of Autism Risk in Babies - Learning Early Signs) mother-child cohort, which enrolls mothers who are either pregnant or planning a pregnancy and whose expected child has an elevated risk to develop ASD. Seven metabolites of organophosphate pesticides were assessed in repeated urine samples collected during pregnancy. At 36 months, children were assessed with intruments measuring cognitive function and adaptive behaviors, and with two gold-standard diagnostic instruments for ASD: the Autism Diagnostic Observation Schedule and the Autism Diagnostic Interview-Revised. Children were classified in one of the following groups: ASD (n = 46), ODC (n = 55) and typically developing (TD, n = 102).

RESULTS

After adjustment for potential confounders, organophosphate metabolite concentrations were not associated with an increased risk of ASD or ODC when boys and girls were studied together. After stratification by sex, dimethylthiophosphate (DMTP) pregnancy concentration tended to be associated with an increased ASD risk among girls (OR for a doubling in the DMTP concentration: 1.64 (95%CI, 0.95; 2.82)) but not among boys (OR: 0.84, 95%CI: 0.63; 1.11).

DISCUSSION

This is the first study of clinically confirmed diagnoses of ASD that utilized repeated measurements of organophosphate metabolites during pregnancy to explore the associations between these pesticides and ASD risk in children. The association we observed among girls, as well as the lack of association in boys, need to be replicated in further studies with similar design and larger sample size. In light of the higher baseline risk for ASD in this cohort, generalizability to children lacking a first degree relative affected by ASD is unknown.