A systematic review of neurodevelopmental effects of prenatal and postnatal organophosphate pesticide exposure

Understanding role of pesticides in development of Parkinson's disease: Insights from Drosophila and rodent models

Parkinson's disease is a neurodegenerative illness linked to ageing, marked by the gradual decline of dopaminergic neurons in the midbrain. The exact aetiology of Parkinson's disease (PD) remains uncertain, with genetic predisposition and environmental variables playing significant roles in the disease's frequency. Epidemiological data indicates a possible connection between pesticide exposure and brain degeneration. Specific pesticides have been associated with important characteristics of Parkinson's disease, such as mitochondrial dysfunction, oxidative stress, and α-synuclein aggregation, which are crucial for the advancement of the disease. Recently, many animal models have been developed for Parkinson's disease study. Although these models do not perfectly replicate the disease's pathology, they provide valuable insights that improve our understanding of the condition and the limitations of current treatment methods. Drosophila, in particular, has been useful in studying Parkinson's disease induced by toxins or genetic factors. The review thoroughly analyses many animal models utilised in Parkinson's research, with an emphasis on issues including pesticides, genetic and epigenetic changes, proteasome failure, oxidative damage, α-synuclein inoculation, and mitochondrial dysfunction. The text highlights the important impact of pesticides on the onset of Parkinson's disease (PD) and stresses the need for more research on genetic and mechanistic alterations linked to the condition.

Pesticides impacts on human health and the environment with their mechanisms of action and possible countermeasures

Pesticides are chemical constituents used to prevent or control pests, including insects, rodents, fungi, weeds, and other unwanted organisms. Despite their advantages in crop production and disease management, the use of pesticides poses significant hazards to the environment and public health. Pesticide elements have now perpetually entered our atmosphere and subsequently contaminated water, food, and soil, leading to health threats ranging from acute to chronic toxicities. Pesticides can cause acute toxicity if a high dose is inhaled, ingested, or comes into contact with the skin or eyes, while prolonged or recurrent exposure to pesticides leads to chronic toxicity. Pesticides produce different types of toxicity, for instance, neurotoxicity, mutagenicity, carcinogenicity, teratogenicity, and endocrine disruption. The toxicity of a pesticide formulation may depend on the specific active ingredient and the presence of synergistic or inert compounds that can enhance or modify its toxicity. Safety concerns are the need of the hour to control contemporary pesticide-induced health hazards. The effectiveness and implementation of the current legislature in providing ample protection for human health and the environment are key concerns. This review explored a comprehensive summary of pesticides regarding their updated impacts on human health and advanced safety concerns with legislation. Implementing regulations, proper training, and education can help mitigate the negative impacts of pesticide use and promote safer and more sustainable agricultural practices.

Neurosteroids as Novel Anticonvulsants for Refractory Status Epilepticus and Medical Countermeasures for Nerve Agents: A 15-Year Journey to Bring Ganaxolone from Bench to Clinic

This article describes recent advances in the use of neurosteroids as novel anticonvulsants for refractory status epilepticus (RSE) and as medical countermeasures (MCs) for organophosphates and chemical nerve agents (OPNAs). We highlight a comprehensive 15-year journey to bring the synthetic neurosteroid ganaxolone (GX) from bench to clinic. RSE, including when caused by nerve agents, is associated with devastating morbidity and permanent long-term neurologic dysfunction. Although recent approval of benzodiazepines such as intranasal midazolam and intranasal midazolam offers improved control of acute seizures, novel anticonvulsants are needed to suppress RSE and improve neurologic function outcomes. Currently, few anticonvulsant MCs exist for victims of OPNA exposure and RSE. Standard-of-care MCs for postexposure treatment include benzodiazepines, which do not effectively prevent or mitigate seizures resulting from nerve agent intoxication, leaving an urgent unmet medical need for new anticonvulsants for RSE. Recently, we pioneered neurosteroids as next-generation anticonvulsants that are superior to benzodiazepines for treatment of OPNA intoxication and RSE. Because GX and related neurosteroids that activate extrasynaptic GABA-A receptors rapidly control seizures and offer robust neuroprotection by reducing neuronal damage and neuroinflammation, they effectively improve neurologic outcomes after acute OPNA exposure and RSE. GX has been selected for advanced, Biomedical Advanced Research and Development Authority-supported phase 3 trials of RSE and nerve agent seizures. In addition, in mechanistic studies of neurosteroids at extrasynaptic receptors, we identified novel synthetic analogs with features that are superior to GX for current medical needs. Development of new MCs for RSE is complex, tedious, and uncertain due to scientific and regulatory challenges. Thus, further research will be critical to fill key gaps in evaluating RSE and anticonvulsants in vulnerable (pediatric and geriatric) populations and military persons. SIGNIFICANCE STATEMENT: Following organophosphate and nerve agent intoxication, refractory status epilepticus (RSE) occurs despite benzodiazepine treatment. RSE occurs in 40% of status epilepticus patients, with a 35% mortality rate and significant neurological morbidity in survivors. To treat RSE, neurosteroids are better anticonvulsants than benzodiazepines. Our pioneering use of neurosteroids for RSE and nerve agents led us to develop ganaxolone as a novel anticonvulsant and neuroprotectant with significantly improved neurological outcomes. This article describes the bench-to-bedside journey of bringing neurosteroid therapy to patients, with ganaxolone leading the way.

A Pediatric Rat Model of Organophosphate-Induced Refractory Status Epilepticus: Characterization of Long-Term Epileptic Seizure Activity, Neurologic Dysfunction and Neurodegeneration

Children are highly vulnerable to the neurotoxic effects of organophosphates (OPs), which can cause neuronal developmental defects, including intellectual disability, autism, epilepsy, and related comorbidities. Unfortunately, no specific pediatric OP neurotoxicity model currently exists. In this study, we developed and characterized a pediatric rat model of status epilepticus (SE) induced by the OP diisopropylfluorophosphate (DFP) and examined its impact on long-term neurological outcomes. Postnatal day 21 rats were exposed to a DFP regimen with standard antidotes. Progressive behavioral deteriorations were assessed over a three-month period. Development of epileptic seizures, ictal discharges, high-frequency oscillations (HFOs), and interictal spikes were monitored by video-electroencephalography recordings. Histology-stereology analysis was performed to assess neurodegeneration, neuroinflammation, and morphologic abnormalities. DFP-exposed, post-SE animals exhibited significantly elevated levels of anxiety and depression than age-matched controls at 1, 2, and 3 months post-exposure. DFP-exposed animals displayed aggressive behavior and a marked decline in object recognition memory, as well as prominent impairment in spatial learning and memory. DFP-exposed animals had striking electrographic abnormalities with the occurrence of displayed epileptic seizures, ictal discharges, HFOs, and interictal spikes, suggesting chronic epilepsy. Neuropathological analysis showed substantially fewer principal neurons and inhibitory interneurons with a marked increase in reactive microglia and neuroinflammation in the hippocampus and other brain regions. DFP-exposed animals also exhibited mossy fiber sprouting indicating impaired network formations. Long-term epileptic seizures and neuropsychiatric functional deficits induced by DFP were consistent with neuropathological defects. Collectively, this pediatric model displays many hallmarks of chronic sequelae reminiscent of children exposed to OPs, suggesting that it will be a valuable tool for investigating pathologic mechanisms and potential treatment strategies to attenuate long-term OP neurotoxicity. SIGNIFICANCE STATEMENT: Millions of children are exposed to organophosphates (OPs) used in agriculture or chemical incidents. This study investigated the long-term impact of neonatal exposure to the OP chemical diisopropylfluorophosphate (DFP) on neurobehavioral and neurodevelopmental outcomes in adulthood. DFP exposure caused long-lasting behavioral abnormalities, epileptic seizures, and bilateral brain defects with an array of neurological sequelae seen in children's OP neurotoxicity. Thus, this model provides a novel tool to explore therapeutic interventions that mitigate long-term neurotoxic effects of children exposed to OP-induced seizures and status epilepticus.

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

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

Effects of additives on the performance of a laser-induced graphene sensor modified with ZrO2 nanoparticles for OP detection

In this study, a simple and portable electrochemical sensor based on laser-induced graphene (LIG) has been developed to systematically investigate the feasibility of LIG as an electrode to detect organophosphorus pesticides (OPs). It proves that the LIG-based electrode has a relatively high electrochemically active surface area (ECSA) and heterogeneous electron transfer (HET) of 0.100 cm2 and 0.000825 cm s-1, respectively. In addition, zirconium dioxide nanoparticles (ZrO2 NPs) have been modified on the electrode with three different binders, β-cyclodextrin (β-CD), chitosan (CS) and Nafion, to improve the adsorption capacity of the electrode toward OPs, and the effect of the binders on the performance of the as-fabricated sensor has been investigated in detail. The results show that β-CD increases not only the electrochemically active surface area of the electrode but also the redox peak current of methyl parathion (MP). To evaluate the sensitivity of the sensor, differential pulse voltammetry (DPV) curves have been tested in solutions containing different concentrations of MP using ZrO2-β-CD/LIG as an electrode, which shows a detection range of 5-200 ng ml-1 and a detection limit of 0.89 ng ml-1. In summary, the LIG-based sensor has a low detection limit, high sensitivity and good interference resistance, and thus has tremendous potential for the detection of pesticides in the environment.

Pregnancy pesticide exposure and child development in low- and middle-income countries: A prospective analysis of a birth cohort in rural Bangladesh and meta-analysis

BACKGROUND

Despite considerable evidence on a negative association between pregnancy pesticide exposure and child development in high-income countries, evidence from low- and middle-income countries (LMICs) is limited. Therefore, we assessed associations between pregnancy pesticide exposure and child development in rural Bangladesh and summarised existing literature in a systematic review and meta-analysis.

METHODS

We used data from 284 mother-child pairs participating in a birth cohort established in 2008. Eight urinary pesticide biomarkers were quantified in early pregnancy (mean gestational age 11.6±2.9 weeks) as an index of pesticide exposure. The Bayley Scales of Infant and Toddler Development, Third Edition were administered at 20-40 months of age. Associations between creatinine-adjusted urinary pesticide biomarker concentrations and child development scores were estimated using multivariable generalised linear models. We searched ten databases up to November 2021 to identify prospective studies on pregnancy pesticide exposure and child development conducted in LMICs. We used a random-effects model to pool similar studies, including our original analysis. The systematic review was pre-registered with PROSPERO: CRD42021292919.

RESULTS

In the Bangladesh cohort, pregnancy 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPY) concentrations were inversely associated with motor development (-0.66 points [95% CI -1.23, -0.09]). Pregnancy 3,5,6-trichloro-2-pyridinol (TCPY) concentrations were inversely associated with cognitive development, but the association was small: -0.02 points (-0.04, 0.01). We observed no associations between 4-nitrophenol and 3-phenoxybenzoic acid (3-PBA) concentrations and child development. The systematic review included 13 studies from four LMICs. After pooling our results with one other study, we found consistent evidence that pregnancy 3-PBA concentrations were not associated with cognitive, language, or motor development.

CONCLUSION

Evidence suggests that pregnancy exposure to some organophosphate pesticides is negatively associated with child development. Interventions to reduce in-utero pesticide exposure in LMICs may help protect child development.

The association of prenatal phthalates, organophosphorous pesticides, and organophosphate esters with early child language ability in Norway

BACKGROUND

Prenatal exposure to phthalates, organophosphate esters, and organophosphorous pesticides have been associated with neurodevelopmental deficits including language ability, however, few studies consider the effect of exposure mixtures and the potential longitudinal detriments over time.

OBJECTIVE

This study examines the influence of prenatal exposure to phthalates, organophosphate esters, and organophosphorous pesticides, on children's language ability from toddlerhood to the preschool period.

METHODS

This study includes 299 mother-child dyads from Norway in the Norwegian Mother, Father and Child Cohort Study (MoBa). Prenatal exposure to chemicals were assessed at 17 weeks' gestation, and child language skills were assessed at 18 months using the Ages and Stages Questionnaire communication subscale and at preschool age using the Child Development Inventory. We ran two structural equation models to examine the simultaneous influences of chemical exposures on parent-reported and teacher-reported child language ability.

RESULTS

Prenatal organophosphorous pesticides were negatively associated with preschool language ability through language ability at 18 months. Additionally, there was a negative association between low molecular weight phthalates and teacher-reported preschool language ability. There was no effect of prenatal organophosphate esters on child language ability at either 18 months or preschool age.

CONCLUSIONS

This study adds to the literature on prenatal exposure to chemicals and neurodevelopment and highlights the importance of developmental pathways in early childhood.

Screening of pesticides in serum, urine and cerebrospinal fluid collected from an urban population in China

Human exposure to pesticides is a topic of public health concern for decades. Pesticide exposures have been assessed through the analysis of urine or blood matrices, but little is known on the accumulation of these chemicals in cerebrospinal fluid (CSF). CSF plays an important role in maintaining physical and chemical balance of the brain and central nervous system and any perturbation can have adverse effects on health. In this study, we investigated the occurrence of 222 pesticides in CSF from 91 individuals using gas chromatography-tandem mass spectrometry (GC-MS/MS). Measured pesticide concentrations in CSF were compared with those in 100 serum and urine specimens from individuals living in the same urban location. Twenty pesticides were found in CSF, serum and urine, at levels above the limit of detection. Three most frequently detected pesticides in CSF were biphenyl (100%), diphenylamine (75%), and hexachlorobenzene (63%). Median concentrations of biphenyl in CSF, serum and urine were 1.11, 10.6, and 1.10 ng/mL, respectively. Six triazole fungicides were found only in CSF, but not in other matrices. To our knowledge, this is the first study to report pesticide concentrations in CSF in a general urban population.

Effective remediation and decontamination of organophosphorus compounds using enzymes: From rational design to potential applications

Organophosphorus compounds (OPs) have been widely used in agriculture for decades because of their high insecticidal efficiency, which maintains and increases crop yields worldwide. More importantly, OPs, as typical chemical warfare agents, are a serious concern and significant danger for military and civilian personnel. The widespread use of OPs, superfluous and unreasonable use, has caused great harm to the environment and food chain. Developing efficient and environmentally friendly solutions for the decontamination of OPs is a long-term challenge. Microbial enzymes show potential application as natural and green biocatalysts. Thus, utilizing OP-degrading enzymes for environmental decontamination presents significant advantages, as these enzymes can rapidly hydrolyze OPs; are environmentally friendly, nonflammable, and noncorrosive; and can be discarded safely and easily. Here, the properties, structure and catalytic mechanism of various typical OP-degrading enzymes are reviewed. The methods and effects utilized to improve the expression level, catalytic performance and stability of OP-degrading enzymes were systematically summarized. In addition, the immobilization of OP-degrading enzymes was explicated emphatically, and the latest progress of cascade reactions based on immobilized enzymes was discussed. Finally, the latest applications of OP-degrading enzymes were summarized, including biosensors, nanozyme mimics and medical detoxification. This review provides guidance for the future development of OP-degrading enzymes and promotes their application in the field of environmental bioremediation and medicine.

Effects of pesticide exposure on oxidative stress and DNA methylation urinary biomarkers in Czech adults and children from the CELSPAC-SPECIMEn cohort

Current-use pesticide (CUP) exposure occurs mainly through diet and environmental application in both agricultural and urban settings. While pesticide exposure has been associated with many adverse health outcomes, the intermediary molecular mechanisms are still not completely elucidated. Among others, their roles in epigenetics (DNA methylation) and DNA damage due to oxidative stress are presumed. Scientific evidence on urinary biomarkers of such body response in general population is limited, especially in children. A total of 440 urine samples (n = 110 parent-child pairs) were collected during the winter and summer seasons in order to describe levels of overall DNA methylation (5-mC, 5-mdC, 5-hmdC, 7-mG, 3-mA) and oxidative stress (8-OHdG) biomarkers and investigate their possible associations with metabolites of pyrethroids (3-PBA, t/c-DCCA), chlorpyrifos (TCPY), and tebuconazole (TEB-OH). Linear mixed-effects models accounting for intraindividual and intrahousehold correlations were utilized. We applied false discovery rate procedure to account for multiplicity and adjusted for potential confounding variables. Higher urinary levels of most biological response biomarkers were measured in winter samples. In adjusted repeated measures models, interquartile range (IQR) increases in pyrethroid metabolites were associated with higher oxidative stress. t/c-DCCA and TCPY were associated with higher urinary levels of cytosine methylation biomarkers (5-mC and/or 5-mdC). The most robust association was observed for tebuconazole metabolite with 3-mA (-15.1% change per IQR increase, 95% CI = -23.6, -5.69) suggesting a role of this pesticide in reduced demethylation processes through possible DNA glycosylase inhibition. Our results indicate an urgent need to extend the range of analyzed environmental chemicals such as azole pesticides (e.g. prothioconazole) in human biomonitoring studies. This is the first study to report urinary DNA methylation biomarkers in children and associations between CUP metabolites and a comprehensive set of biomarkers including methylated and oxidized DNA alterations. Observed associations warrant further large-scale research of these biomarkers and environmental pollutants including CUPs.

Sauver JL, Rocca WA. Integrating Environmental Data with Medical Data in a Records-Linkage System to Explore Groundwater Nitrogen Levels and Child Health Outcomes

Background: The Rochester Epidemiology Project (REP) medical records-linkage system offers a unique opportunity to integrate medical and residency data with existing environmental data, to estimate individual-level exposures. Our primary aim was to provide an archetype of this integration. Our secondary aim was to explore the association between groundwater inorganic nitrogen concentration and adverse child and adolescent health outcomes. Methods: We conducted a nested case-control study in children, aged seven to eighteen, from six counties of southeastern Minnesota. Groundwater inorganic nitrogen concentration data were interpolated, to estimate exposure across our study region. Residency data were then overlaid, to estimate individual-level exposure for our entire study population (n = 29,270). Clinical classification software sets of diagnostic codes were used to determine the presence of 21 clinical conditions. Regression models were adjusted for age, sex, race, and rurality. Results: The analyses support further investigation of associations between nitrogen concentration and chronic obstructive pulmonary disease and bronchiectasis (OR: 2.38, CI: 1.64-3.46) among boys and girls, thyroid disorders (OR: 1.44, CI: 1.05-1.99) and suicide and intentional self-inflicted injury (OR: 1.37, CI: >1.00-1.87) among girls, and attention deficit conduct and disruptive behavior disorders (OR: 1.34, CI: 1.24-1.46) among boys. Conclusions: Investigators with environmental health research questions should leverage the well-enumerated population and residency data in the REP.

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.

Maternal and paternal employment in agriculture and early childhood development: A cross-sectional analysis of Demographic and Health Survey data

Considerable literature from low- and lower-middle-income countries (LLMICs) links maternal employment to child nutritional status. However, less is known about the role of parental employment and occupation type in shaping child development outcomes. Additionally, little empirical work has examined the mechanisms through which parental occupation influences child outcomes. Our objective was to investigate the associations between maternal and paternal employment (comparing agricultural and non-agricultural employment) and child development and to examine childcare practices and women's empowerment as potential mechanisms. We pooled nine Demographic and Health Surveys (Benin, Burundi, Cambodia, Congo, Haiti, Rwanda, Senegal, Togo, and Uganda) with data on 8,516 children aged 36-59 months. We used generalised linear models to estimate associations between parental employment and child development, child stimulation (number of activities provided by the mother, father, and other household members), child supervision (not left alone or with older child for >1 hour), early childhood care and education programme (ECCE) attendance, and women's empowerment. In our sample, all fathers and 85% of mothers were employed. In 40% of families, both parents were employed in agriculture. After adjusting for child, parental and household confounders, we found that parental agricultural employment, relative to non-agricultural employment, was associated with poorer child development (relative risk (RR) 0.86 (95% CI 0.80, 0.92), more child stimulation provided by other household members (mean difference (MD) 0.26 (95% CI 0.09, 0.42)), less adequate child supervision (RR, 0.83 (95% 0.78, 0.80)), less ECCE attendance (RR 0.46 (95% CI 0.39, 0.54)), and lower women's empowerment (MD -1.01 (95% CI -1.18, -0.84)). Parental agricultural employment may be an important risk factor for early childhood development. More research using more comprehensive exposure and outcome measures is needed to unpack these complex relationships and to inform interventions and policies to support working parents in the agricultural sector with young children.

Residues of pesticides and veterinary drugs in diets of dairy cattle from conventional and organic farms in Austria

Modern agriculture depends highly on pesticides and pharmaceutical preparations, so controlling exposure to these substances in the feed and food chain is essential. This article presents the first study on residues of a broad spectrum of pesticides and veterinary drugs in the diets of dairy cattle. One hundred and two representative samples of the complete diets, including basal feed rations and additional fed concentrate, were collected in three Austrian provinces (Styria, Lower and Upper Austria) in 2019 and 2020. The samples were tested for >700 pesticides, veterinary drugs and related metabolites using a validated method based on liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS). In total, 16 residues (13 pesticides and three veterinary drug residues) were detected. > 90% of the diets contained pesticide residues and <10% veterinary drug residues, whereas banned pesticides were not found. The most frequent pesticide residues were fluopyram (62%), piperonyl butoxide (39%) and diethyltoluamide (35%). The following pesticides exceed the default EU maximum residue level (MRL) (10 μg kg^-1) for products exclusively used for animal feed production: Benzovindiflupyr (proportion of samples > MRLs: 1%), bixafen (2%), fluopyram (6%), ipconazole (1%) and tebuconazole (3%). Three residues (dinitrocarbanilide, monensin and nicarbazin) of veterinary drugs were identified, all below the MRLs. Over 60% of the evaluated samples contained mixtures of two to six residues/sample. Only one pesticide (diethyltoluamide) presented a significant difference among regions, with higher concentrations in Upper Austria. Brewery's spent grains were the dietary ingredient that showed the strongest correlation to pesticide residues. These findings evidence the realistic scenario of highly occurrent low doses of pesticides cocktails in the feed/food chain, which may affect the animal, human and environmental health. Since the risk assessments are based on single pesticides, the potential synergistic effect of co-occurring chemicals ("cocktail effect") requires further investigations.

Effects of Pesticide Intake on Gut Microbiota and Metabolites in Healthy Adults

Animal experiments have indicated that pesticides may affect gut microbiota, which is responsible for the production of short-chain fatty acids (SCFAs) and polyamines. Here, we present a preliminary observation of the relationship between pesticide exposure and fecal SCFAs and polyamines in Japanese adults. In total, 38 healthy adults aged 69 ± 10 years (mean ± SD) were recruited and subjected to stool and spot urine tests. Urinary dialkylphosphates (DAP), 3-phenoxybenzoic acid, and glyphosate were assayed as pesticide exposure markers of organophosphorus insecticide (OP), a pyrethroid insecticide, and glyphosate, respectively. Significant negative correlations (p < 0.05, Spearman’s rank correlation coefficient) were found between urinary DAP, fecal acetate (r = −0.345), and lactate (r = −0.391). Multiple regression analyses revealed that urinary DAP was a significant explanatory variable of fecal acetate concentration (p < 0.001, β = −24.0, SE = 4.9, t = −4.9) with some vegetable intake (adjusted R-square = 0.751). These findings suggest that OP exposure is independently associated with lower fecal acetate levels, which may contribute to human health in middle-aged and older adult groups. Given that the human gut environment has long-term effects on the host, studies on wide-range age groups, including children, are necessary.

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

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

Pesticide exposure and child growth in low- and middle-income countries: A systematic review

BACKGROUND

In low- and middle-income countries (LMICs), pesticides are widely used in agricultural and residential settings. Little is known about how pesticides affect child growth.

OBJECTIVES

To systematically review and synthesise the evidence on the associations between pesticide exposure and adverse birth outcomes and/or impaired postnatal growth in children up to 5 years of age in LMICs.

METHODS

We searched 10 databases from inception through November 2021. We included cohort and cross-sectional studies investigating associations between self-reported or measured prenatal or postnatal pesticide exposure and child growth (postnatal child linear/ponderal growth, and/or birth outcomes). Two researchers screened studies, extracted data, and assessed certainty using GRADE. The protocol was preregistered with PROSPERO (CRD42021292919).

RESULTS

Of 939 records retrieved, 31 studies met inclusion criteria (11 cohort, 20 cross-sectional). All studies assessed prenatal exposure. Twenty-four studies reported on birth weight. Four found positive associations with organochlorines (0.01-0.25 standardised mean difference (SMD)) and two found negative associations (-0.009 SMD to -55 g). Negative associations with organophosphates (-170 g, n = 1) and pyrethroids (-97 to -233 g, n = 2) were also documented. Two (out of 15) studies reporting on birth length found positive associations with organochlorines (0.21-0.25 SMD) and one found negative associations (-0.25 to -0.32 SMD). Organophosphate exposure was negatively associated with birth length (-0.37 cm, n = 1). Organophosphate exposure was also associated with higher risk/prevalence of low birth weight (2 out of nine studies) and preterm birth (2 out of six studies). Certainty of the evidence was "very low" for all outcomes.

CONCLUSION

The limited literature from LMICs shows inconclusive associations between prenatal pesticide exposure, child growth, and birth outcomes. Studies with accurate quantitative data on exposure to commonly used pesticides in LMICs using consistent methodologies in comparable populations are needed to better understand how pesticides influence child growth.

Bioactivation and detoxification of organophosphorus pesticides in freshwater planarians shares similarities with humans

Organophosphorus pesticides (OPs) are a chemically diverse class of insecticides that inhibit acetylcholinesterase (AChE). Many OPs require bioactivation to their active oxon form via cytochrome P450 to effectively inhibit AChE. OP toxicity can be mitigated by detoxification reactions performed by carboxylesterase and paraoxonase. The relative extent of bioactivation to detoxification varies among individuals and between species, leading to differential susceptibility to OP toxicity. Because of these species differences, it is imperative to characterize OP metabolism in model systems used to assess OP toxicity. We have shown that the asexual freshwater planarian Dugesia japonica is a suitable model to assess OP neurotoxicity and developmental neurotoxicity via rapid, automated testing of adult and developing organisms in parallel using morphological and behavioral endpoints. D. japonica has two cholinesterase enzymes with intermediate properties between AChE and butyrylcholinesterase that are sensitive to OP inhibition. Here, we demonstrate that D. japonica contains the major OP metabolic machinery to be a relevant model for OP neurotoxicity studies. Adult and regenerating D. japonica can bioactivate chlorpyrifos and diazinon into their respective oxons. Significant AChE inhibition was only observed after in vivo metabolic activation but not when the parent OPs were directly added to planarian homogenate using the same concentrations and timing. Using biochemical assays, we found that D. japonica has both carboxylesterase (24 nmol/(min*mg protein)) and paraoxonase (60 pmol/(min*mg protein)) activity. We show that planarian carboxylesterase activity is distinct from cholinesterase activity using benzil and tacrine. These results further support the use of D. japonica for OP toxicity studies.

Pesticide exposure among Czech adults and children from the CELSPAC-SPECIMEn cohort: Urinary biomarker levels and associated health risks

Current-use pesticides (CUP) are extensively applied in both agricultural and urban settings. Exposure occurs mainly via the dietary pathway; however, other pathways such as inhalation or skin contact are also important. In this study, urinary levels of 12 CUP metabolites were investigated among 110 parent-child pairs during two seasons of 2020. Metabolites of pyrethroids (3-PBA, t/c-DCCA), chlorpyrifos (TCPY), and tebuconazole (TEB-OH) were detected in more than 60% of the samples. Chlorpyrifos metabolite was found at the highest concentration and tebuconazole was detected in almost all samples. CUP urinary metabolite levels were significantly higher in children in comparison to adults, except for tebuconazole, which was similar in both groups. In children, winter samples had significantly higher concentrations of pyrethroid and chlorpyrifos metabolites in comparison to the summer samples, but in adults, only chlorpyrifos metabolite concentrations were higher in the winter. No association between CUP urinary metabolite levels and proximity/surface of agricultural areas around residences was observed. Based on our findings, we suspect that CUP exposure is mainly driven by diet and that the effect of environmental exposure is less significant. Daily Intakes were estimated with three possible scenarios considering the amount of the metabolite excreted in urine and were compared to Acceptable Daily Intake values. Using a realistic scenario, exposure to chlorpyrifos exhibited the highest health risk, but still within a safe level. The Acceptable Daily Intake was exceeded only in one child in the case of cypermethrin. The cumulative risk assessment of pesticide mixtures having an effect on the nervous system, based on the total margin of exposure calculations, did not indicate any risk. The overall risk associated with pesticide exposure in the observed population was low. However, the risk observed using the worst-case scenario suggests the need for continuous evaluation of human exposure to such compounds, especially in children.

Domestic Exposure to Chemicals in Household Products, Building Materials, Decoration, and Pesticides: Guidelines for Interventions During the Perinatal Period from the French National College of Midwives

INTRODUCTION

We are exposed to numerous pollutants inside our homes. The perinatal period represents a particular window of vulnerability during which these exposures can have negative health effects over a more or less long term. The objective of this article is to formulate guidelines for health care professionals and intended for parents to reduce exposure to chemical pollutants at home, based on the scientific literature and already existing guidelines.

METHODS

We have followed the methodological procedures set forth by the French authority for health (HAS) to establish guidelines to limit exposure to pollutants in homes. This narrative review of the scientific literature was conducted with two principal objectives: (1) to identify priority substances emitted within homes and that have a reprotoxic potential and (2) to identify measures to limit exposure to these residential pollutants. The guidelines were developed from the data in the literature and from advice already made available by diverse institutions about environmental health during the perinatal period.

RESULTS

Domestic pollutants are numerous and come from both common (that is, shared, eg, painting, cleaning, and maintenance work) and specific (use of household pesticides) sources. Numerous pollutants are suspected or known to produce developmental toxicity, that is, to be toxic to children during developmental stages. Removing some products from the home, protecting the vulnerable (ie, pregnant women and young children) from exposure, and airing the home are among the preventive measures proposed to limit exposure to these chemical substances.

CONCLUSION

Health care professionals can provide advice to parents during the perinatal period to diminish exposure to household pollutants. The lack of interventional studies nonetheless limits the level of evidence for most of these recommendations.

An assessment of exposure to several classes of pesticides in pet dogs and cats from New York, United States

Exposure of pet dogs and cats to pesticides used in and around homes (e.g., lawns and gardens) is a significant health concern. Furthermore, some pesticides are directly used on dogs and cats for flea, lice, and tick control. Despite this, little is known regarding the extent of pesticide exposure in pets. In this study, we determined the concentrations of 30 biomarkers of pesticide exposure in urine collected from dogs and cats in New York State, USA: 6 dialkylphosphate (DAP) metabolites of organophosphates (OPs); 14 neonicotinoids (neonics); 3 specific metabolites of OPs; 5 pyrethroids (PYRs); and 2 phenoxy acids (PAs). The sum median concentrations of these 30 pesticide biomarkers (ΣPesticides) in dog and cat urine were 35.2 and 38.1 ng/mL, respectively. Neonics were the most prevalent in dogs (accounting for 43% of the total concentrations), followed by DAPs (17%), PYRs (16%), OPs (13%), and PAs (∼10%). In cat urine, neonics alone accounted for 83% of the total concentrations. Elevated concentrations of imidacloprid were found in the urine of certain dogs (max: 115 ng/mL) and cats (max: 1090 ng/mL). Some pesticides showed gender- and sampling location- related differences in urinary concentrations. We calculated daily exposure doses of pesticides from the measured urinary concentrations through a reverse dosimetry approach. The estimated daily intakes (DIs) of chlorpyrifos, diazinon, and cypermethrin were above the chronic reference doses (cRfDs) in 22, 76, and 5%, respectively, of dogs. The DIs of chlorpyrifos, parathion, diazinon, and imidacloprid were above the cRfDs in 33, 14, 100, and 29%, respectively, of cats. This study thus provides evidence that pet dogs and cats are exposed to certain pesticides at levels that warrant immediate attention.

Differences in neurotoxic outcomes of organophosphorus pesticides revealed via multi-dimensional screening in adult and regenerating planarians

Organophosphorus pesticides (OPs) are a chemically diverse class of commonly used insecticides. Epidemiological studies suggest that low dose chronic prenatal and infant exposures can lead to life-long neurological damage and behavioral disorders. While inhibition of acetylcholinesterase (AChE) is the shared mechanism of acute OP neurotoxicity, OP-induced developmental neurotoxicity (DNT) can occur independently and/or in the absence of significant AChE inhibition, implying that OPs affect alternative targets. Moreover, different OPs can cause different adverse outcomes, suggesting that different OPs act through different mechanisms. These findings emphasize the importance of comparative studies of OP toxicity. Freshwater planarians are an invertebrate system that uniquely allows for automated, rapid and inexpensive testing of adult and developing organisms in parallel to differentiate neurotoxicity from DNT. Effects found only in regenerating planarians would be indicative of DNT, whereas shared effects may represent neurotoxicity. We leverage this unique feature of planarians to investigate potential differential effects of OPs on the adult and developing brain by performing a comparative screen to test 7 OPs (acephate, chlorpyrifos, dichlorvos, diazinon, malathion, parathion and profenofos) across 10 concentrations in quarter-log steps. Neurotoxicity was evaluated using a wide range of quantitative morphological and behavioral readouts. AChE activity was measured using an Ellman assay. The toxicological profiles of the 7 OPs differed across the OPs and between adult and regenerating planarians. Toxicological profiles were not correlated with levels of AChE inhibition. Twenty-two "mechanistic control compounds" known to target pathways suggested in the literature to be affected by OPs (cholinergic neurotransmission, serotonin neurotransmission, endocannabinoid system, cytoskeleton, adenyl cyclase and oxidative stress) and 2 negative controls were also screened. When compared with the mechanistic control compounds, the phenotypic profiles of the different OPs separated into distinct clusters. The phenotypic profiles of adult vs. regenerating planarians exposed to the OPs clustered differently, suggesting some developmental-specific mechanisms. These results further support findings in other systems that OPs cause different adverse outcomes in the (developing) brain and build the foundation for future comparative studies focused on delineating the mechanisms of OP neurotoxicity in planarians.

Maternal occupational exposure to chemicals and child cognitive function

BACKGROUND

Limited data exist regarding child neurodevelopment in relation to maternal occupational exposure to endocrine-disrupting chemicals (EDCs).

METHODS

We included 1058 mother-child pairs from the INfancia y Medio Ambiente (INMA) project (2003-2008). Using a job-exposure matrix, exposure probability scores for ten EDC groups were assigned to each mother based on her longest held job during pregnancy. At the child's 5-year visit, the McCarthy Scales of Children's Abilities was administered, yielding the general cognitive index and scales for specific cognitive domains. We analyzed region-specific associations between EDC exposures and each outcome separately using adjusted linear regression and combined region-specific effect estimates using random-effects meta-analyses.

RESULTS

Approximately 24% of women were exposed to at least one EDC group, but exposure to most individual EDC groups was low (<5%). Maternal organic solvent exposure was associated with lower quantitative scores among children (-5.8 points, 95% confidence interval: -11.0, -0.5). Though statistically non-significant, exposures to polycyclic aromatic hydrocarbons, phthalates, alkylphenolic compounds, and miscellaneous chemicals were associated with poorer offspring performance for most or all cognitive domains.

CONCLUSIONS

This study found limited evidence for a role of maternal occupational EDC exposures on child cognition. Further research is needed to better characterize exposures among pregnant workers.

IMPACT

Using data from a prospective birth cohort, we help fill an important research gap regarding the potential consequences of work-related exposure to endocrine-disrupting chemicals (EDCs) among pregnant women on child neurodevelopment. We expand on existing literature-largely limited to pesticide and organic solvent exposures-by using a job-exposure matrix to estimate exposure to several EDC groups. We found limited evidence of an association between maternal occupational EDC exposure and children's overall cognition. We did observe specific associations between exposure to organic solvents and lower quantitative reasoning scores.

Health Effects of Pesticide Exposure in Latin American and the Caribbean Populations: A Scoping Review

BACKGROUND

Multiple epidemiological studies have shown that exposure to pesticides is associated with adverse health outcomes. However, the literature on pesticide-related health effects in the Latin American and the Caribbean (LAC) region, an area of intensive agricultural and residential pesticide use, is sparse. We conducted a scoping review to describe the current state of research on the health effects of pesticide exposure in LAC populations with the goal of identifying knowledge gaps and research capacity building needs.

METHODS

We searched PubMed and SciELO for epidemiological studies on pesticide exposure and human health in LAC populations published between January 2007 and December 2021. We identified 233 publications from 16 countries that met our inclusion criteria and grouped them by health outcome (genotoxicity, neurobehavioral outcomes, placental outcomes and teratogenicity, cancer, thyroid function, reproductive outcomes, birth outcomes and child growth, and others).

RESULTS

Most published studies were conducted in Brazil (37%, n = 88 ) and Mexico (20%, n = 46 ), were cross-sectional in design (72%, n = 167 ), and focused on farmworkers (45%, n = 105 ) or children (21%, n = 48 ). The most frequently studied health effects included genotoxicity (24%, n = 62 ) and neurobehavioral outcomes (21%, n = 54 ), and organophosphate (OP) pesticides were the most frequently examined (26%, n = 81 ). Forty-seven percent (n = 112 ) of the studies relied only on indirect pesticide exposure assessment methods. Exposure to OP pesticides, carbamates, or to multiple pesticide classes was consistently associated with markers of genotoxicity and adverse neurobehavioral outcomes, particularly among children and farmworkers.

DISCUSSION

Our scoping review provides some evidence that exposure to pesticides may adversely impact the health of LAC populations, but methodological limitations and inconsistencies undermine the strength of the conclusions. It is critical to increase capacity building, integrate research initiatives, and conduct more rigorous epidemiological studies in the region to address these limitations, better inform public health surveillance systems, and maximize the impact of research on public policies. https://doi.org/10.1289/EHP9934.

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

INTRODUCTION

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Exposure to non-persistent pesticides, BDNF, and behavioral function in adolescent males: Exploring a novel effect biomarker approach

BACKGROUND

Numerous contemporary non-persistent pesticides may elicit neurodevelopmental impairments. Brain-derived neurotrophic factor (BDNF) has been proposed as a novel effect biomarker of neurological function that could help to understand the biological responses of some environmental exposures.

OBJECTIVES

To investigate the relationship between exposure to various non-persistent pesticides, BDNF, and behavioral functioning among adolescents.

METHODS

The concentrations of organophosphate (OP) insecticide metabolites 3,5,6-trichloro-2-pyridinol (TCPy), 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPy), malathion diacid (MDA), and diethyl thiophosphate (DETP); metabolites of pyrethroids 3-phenoxybenzoic acid (3-PBA) and dimethylcyclopropane carboxylic acid (DCCA), the metabolite of insecticide carbaryl 1-naphthol (1-N), and the metabolite of ethylene-bis-dithiocarbamate fungicides ethylene thiourea (ETU) were measured in spot urine samples, as well as serum BDNF protein levels and blood DNA methylation of Exon IV of BDNF gene in 15-17-year-old boys from the INMA-Granada cohort in Spain. Adolescents' behavior was reported by parents using the Child Behavior Check List (CBCL/6-18). This study included 140 adolescents of whom 118 had data on BDNF gene DNA methylation. Multivariable linear regression, weighted quantile sum (WQS) for mixture effects, and mediation models were fit.

RESULTS

IMPy, MDA, DCCA, and ETU were detected in more than 70% of urine samples, DETP in 53%, and TCPy, 3-PBA, and 1-N in less than 50% of samples. Higher levels of IMPy, TCPy, and ETU were significantly associated with more behavioral problems as social, thought problems, and rule-breaking symptoms. IMPy, MDA, DETP, and 1-N were significantly associated with decreased serum BDNF levels, while MDA, 3-PBA, and ETU were associated with higher DNA methylation percentages at several CpGs. WQS models suggest a mixture effect on more behavioral problems and BDNF DNA methylation at several CpGs. A mediated effect of serum BDNF within IMPy-thought and IMPy-rule breaking associations was suggested.

CONCLUSION

BDNF biomarkers measured at different levels of biological complexity provided novel information regarding the potential disruption of behavioral function due to contemporary pesticides, highlighting exposure to diazinon (IMPy) and the combined effect of IMPy, MDA, DCCA, and ETU. However, further research is warranted.

Urinary organophosphate metabolite concentrations and birth sizes among women conceiving through in vitro fertilization in Shanghai, China

BACKGROUND

Few studies have examined the adverse birth sizes of preconception exposure to organophosphate pesticides (OPs) in women undergoing in vitro fertilization (IVF).

OBJECTIVES

We investigated the relationship of preconception OP exposure with birth sizes among Chinese women undergoing IVF.

METHODS

This study included 302 couples seeking infertility treatment in the China National Birth Cohort Study, from Shanghai, China, who gave birth to singleton infants between 2018 and 2021. Clinical data were collected from medical records. We measured the concentrations of six nonspecific dialkyl phosphates (DAP) metabolites of OPs [diethylthiophosphate (DETP), diethylphosphate (DEP), diethyldithiophosphate (DEDTP), dimethyldithiophosphate (DMTP), dimethylphosphate (DMP), and dimethyldithiophosphate (DMDTP)] in maternal urine. DMDTP and DEDTP were precluded from further analyses due to the low detection rates. Generalized linear models (GLMs) and weighted quantile sum (WQS) regression analyses were performed to examine the individual and joint effects of OP exposures on gestational age, birth weight, body length, and ponderal index. Odder ratio (OR) of preterm birth were estimated using logistic regression models.

RESULTS

Women in the highest as compared with lowest quartile of DEP had shorter gestational age (β = - 0.68; 95% CI = -1.24, -0.11). The association was modified by sex, with boys showing larger decreases in gestational age (β = - 0.86; 95% CI = -1.60, -0.13). No associations were found between other DAP metabolites and birth sizes. Results from linear models with individual DAP metabolites were corroborated by the WQS regression where DEP had the largest contribution to the overall mixture effect on gestational age (weight = 0.70). Moreover, DEP concentration was associated with an elevated risk of preterm birth (OR = 1.35, 95% CI = 1.11, 2.25).

CONCLUSION

Preconception DEP concentration was associated with shortened gestational age and increased risk of preterm birth, and the association was more pronounced among boys than girls.

The growing concern of chlorpyrifos exposures on human and environmental health

Chlorpyrifos (CP) and its highly electrophilic intermediates are principal toxic metabolites. The active form of CP i.e. chlorpyrifos oxon (CP-oxon) is responsible for both the insecticidal activity and is also of greater risk when present in the atmosphere. Thus, the combined effects of both CP, CP-oxan, and other metabolites enhance our understanding of the safety and risk of the insecticide CP. They cause major toxicities such as AChE inhibition, oxidative stress, and endocrine disruption. Further, it can have adverse hematological, musculoskeletal, renal, ocular, and dermal effects. Excessive use of this compound results in poisoning and potentially kills a non-target species upon exposure including humans. Several examples of reactive metabolites toxicities on plants, aquatic life, and soil are presented herein. The review covers the general overview on reactive metabolites of CP, chemistry and their mechanism through toxic effects on humans as well as on the environment. Considerable progress has been made in the replacement or alternative to CP. The different strategies including antidote mechanisms for the prevention and treatment of CP poisoning are discussed in this review. The approach analyses also the active metabolites for the pesticide activity and thus it becomes more important to know the pesticide and toxicity dose of CP as much as possible.

Anesthetic Exposure During Childhood and Neurodevelopmental Outcomes: A Systematic Review and Meta-analysis

IMPORTANCE

Clinical studies of neurodevelopmental outcomes after anesthetic exposure have evaluated a range of outcomes with mixed results.

OBJECTIVE

To examine via meta-analyses the associations between exposure to general anesthesia and domain-specific neurodevelopmental outcomes in children.

DATA SOURCES

PubMed/MEDLINE, Embase, CINAHL, Web of Science and the Cochrane Library were searched from inception to August 31, 2021.

STUDY SELECTION

Inclusion criteria were exposures to procedures requiring general anesthesia at younger than 18 years and evaluation of long-term neurodevelopmental function after exposure. Studies lacking unexposed controls or focused on children with major underlying comorbidities were excluded.

DATA EXTRACTION AND SYNTHESIS

Extracted variables included effect size; hazard, risk, or odds ratio; number of exposures; procedure type; major comorbidities; age of exposure and assessment; presence of unexposed controls; and study design. Studies were independently reviewed by 2 coders, and review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data were pooled using a random-effects model.

MAIN OUTCOMES AND MEASURES

The main outcomes were standardized mean differences (SMD) for scores in the neurodevelopmental domains of academics, behavioral problems, cognition, executive function, general development, language, motor function, nonverbal reasoning, social cognition, and hazard and risk of neurodevelopmental disorder diagnoses.

RESULTS

A total of 31 studies contributed data for meta-analysis. For each of the assessed neurodevelopmental domains, the numbers of children evaluated ranged from 571 to 63 315 exposed and 802 to 311 610 unexposed. Children with any exposure (single or multiple) had significantly worse behavioral problems scores, indicating more behavioral problems (SMD, -0.10; 95% CI, -0.18 to -0.02; P = .02), and worse scores in academics (SMD, -0.07; 95% CI -0.12 to -0.01; P = .02), cognition (SMD, -0.03; 95% CI, -0.05 to 0.00; P = .03), executive function (SMD, -0.20; 95% CI, -0.32 to -0.09; P < .001), general development (SMD, -0.08; 95% CI, -0.13 to -0.02; P = .01), language (SMD, -0.08; 95% CI, -0.14 to -0.02; P = .01), motor function (SMD, -0.11; 95% CI, -0.21 to -0.02; P = .02), and nonverbal reasoning (SMD, -0.15; 95% CI, -0.27 to -0.02; P = .02). Higher incidences of neurodevelopmental disorder diagnoses were also reported (hazard ratio, 1.19; 95% CI, 1.09 to 1.30; P < .001; risk ratio, 1.81; 95% CI, 1.25 to 2.61; P = .002).

CONCLUSIONS AND RELEVANCE

These findings support the hypothesis that associations between anesthetic exposure during childhood and subsequent neurodevelopmental deficits differ based on neurodevelopmental domain.

Comparing impact of pesticide exposure on cognitive abilities of Latinx children from rural farmworker and urban non-farmworker families in North Carolina

Pesticide exposure remains a health hazard despite extensive study into adverse effects. Children in vulnerable populations, such as Latinx children in farmworker families, are particularly at risk for exposure. Several studies have demonstrated the detrimental cognitive effects of prenatal exposure to pesticides, particularly organophosphates (OPs) within this high-risk group. However, results from studies investigating the cognitive effects of early childhood pesticide exposure are equivocal. Most studies examining the effects of pesticide exposure have used correlative analyses rather than examining populations with expected high and low exposure. The current study compares 8-year-old children from rural families of farmworkers and urban, non-farmworker families. We used the Weschler Intelligence Scale for Children - Fifth Edition (WISC-V) to assess cognitive performance in these children. We designed this study with the expectation that children from farmworker families would have greater exposure to agricultural pesticides than urban, non-farmworker children. This assumption of exposure to agricultural pesticides was confirmed in a recent report that assessed exposure probabilities using life history calendars. However, data from passive wristband sampling of acute (1-week) pesticide exposure from these same children indicate that both study populations have considerable pesticide exposure but to different chemicals. As expected the children of farmworkers had greater OP exposure than non-farmworker children, but the non-farmworker children had greater exposure to two other classes of insecticides (organochlorines [OCs] and pyrethroids). Our analyses considered these findings. A comparison of the cognitive scores between groups revealed that children from farmworker families had slightly higher performance on the Visual-Spatial Index (VSI) and Verbal Comprehension Index (VCI) when compared to children from non-farmworker families. Regression analyses where pesticide exposure was included as covariates revealed that OC exposure accounted for the largest portion of the group differences for both VSI and VCI. However, a post-hoc moderation analysis did not find significant interactions. The main study outcome was that the non-farmworker children exhibited lower WISC-V scores than the children from farmworker families, and the analyses incorporating pesticide exposure measures raise the hypothesis the that pervasive and persistent nature of a variety of pesticides may have adverse effects on the neurodevelopment of young Latinx children whether living in rural or non-farmworker environments.

Parental Occupational Exposure and Neurodevelopmental Disorders in Offspring: a Systematic Review and Meta-analysis

PURPOSE OF REVIEW

Parental occupational exposures might be associated with neurodevelopmental disorders (NDDs) in offspring. We aimed to conduct a systematic review and meta-analysis to summarize and synthesize the current literature and to estimate the pooled magnitude of the underlying association(s) between parental occupational exposures and subsequent risk of NDDs.

RECENT FINDINGS

In the meta-analysis of 20 included studies, significant associations were found between parental occupational exposure to pesticides or solvents and the risk of attention deficit hyperactivity disorder in offspring. Prenatal occupational exposure to pesticides was significantly associated with motor development or cognition disorders in children. Furthermore, some evidence showed that metals might have a role in the development of autism spectrum disorders. Further studies need to identify the level of parental occupational exposures that can be significantly associated with NDDs. Moreover, utilizing standardized outcome and exposure scales is recommended to incorporate paternal, maternal, and parental as well as both prenatal and postnatal exposure in future studies.

Impact of High-Throughput Model Parameterization and Data Uncertainty on Thyroid-Based Toxicological Estimates for Pesticide Chemicals

Chemical-induced alteration of maternal thyroid hormone levels may increase the risk of adverse neurodevelopmental outcomes in offspring. US federal risk assessments rely almost exclusively on apical endpoints in animal models for deriving points of departure (PODs). New approach methodologies (NAMs) such as high-throughput screening (HTS) and mechanistically informative in vitro human cell-based systems, combined with in vitro to in vivo extrapolation (IVIVE), supplement in vivo studies and provide an alternative approach to calculate/determine PODs. We examine how parameterization of IVIVE models impacts the comparison between IVIVE-derived equivalent administered doses (EADs) from thyroid-relevant in vitro assays and the POD values that serve as the basis for risk assessments. Pesticide chemicals with thyroid-based in vitro bioactivity data from the US Tox21 HTS program were included (n = 45). Depending on the model structure used for IVIVE analysis, up to 35 chemicals produced EAD values lower than the POD. A total of 10 chemicals produced EAD values higher than the POD regardless of the model structure. The relationship between IVIVE-derived EAD values and the in vivo-derived POD values is highly dependent on model parameterization. Here, we derive a range of potentially thyroid-relevant doses that incorporate uncertainty in modeling choices and in vitro assay data.

Combined Effects of Potassium Perchlorate and a Neonicotinoid on Zebrafish Larvae (Danio rerio)

Imidacloprid (IMI) is part of the neonicotinoids family, insecticides widely used by humans and also found in wastewater. This class of compounds, if present in the environment, can cause toxicity to different species such as bees and gammarids, although little is known about vertebrates such as fish. In addition, several substances have been reported in the environment that can cause damage to aquatic species, such as potassium perchlorate (KClO₄), if exposed to high concentrations or for long periods. Often, the co-presence of different contaminants can cause a synergistic action in terms of toxicity to fish. In the present study, we first analyzed different concentrations of IMI (75, 100 and 150 mg/L) and KClO₄ (1, 1.5 and 5 mM) to highlight the morphological effects at 96 hpf and, subsequently, chose two nontoxic concentrations to evaluate their co-exposure and the pathway involved in their co-toxicity. Morphological alteration, mucus production, messenger RNA (mRNA) expression related to intestinal function and oxidative stress were measured. These results suggest that co-exposure to IMI and KClO₄ could affect zebrafish embryo development by increasing gut toxicity and the alteration of antioxidative defense mechanisms.

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

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

Quantitative analysis of organophosphate pesticides and dialkylphosphates in duplicate diet samples to identify potential sources of measured urinary dialkylphosphates in Japanese women

Increased levels of dialkylphosphates (DAP) in maternal urine are associated with a variety of adverse developmental outcomes in children. Although urinary DAP levels are usually considered to be a marker of exposure to organophosphate (OP) pesticides, excretion of DAP may also increase by ingesting preformed DAP. To date, no study has quantitatively assessed the possible contribution of the dietary intake of preformed DAP and OP pesticides to urinary levels of DAP. Therefore, we aimed to estimate the levels of 6 DAPs and 84 OP pesticides in duplicate diet samples and urine samples collected from 73 women living in urban areas of Japan in 2018. DAP and OP pesticides were detected in 94% and 45% of diet samples, while DAP was detected in 100% of urinary samples, respectively. The average daily intake of preformed DAP was significantly higher than that of parent OP pesticides in our participants. Dimethylphosphate and diethylphosphate were predominant in the preformed DAP, and the estimated average daily intake of total amount of DAP was 78.3 nmol. Fruits and vegetables were the major dietary sources of DAP. Dietary intake of DAP was positively associated with urinary DAP levels, suggesting that a considerable amount of urinary DAP was derived from ingesting preformed DAP. Our results show that attributing urinary DAP levels exclusively to OP pesticide exposure would result in a substantial overestimation of the exposure level. Therefore, the urinary levels of DAP may not be suitable for evaluating OP pesticide exposure in the general urban population.

Risk Factors for Brain Health in Agricultural Work: A Systematic Review

Certain exposures related to agricultural work have been associated with neurological disorders. To date, few studies have included brain health measurements to link specific risk factors with possible neural mechanisms. Moreover, a synthesis of agricultural risk factors associated with poorer brain health outcomes is missing. In this systematic review, we identified 106 articles using keywords related to agriculture, occupational exposure, and the brain. We identified seven major risk factors: non-specific factors that are associated with agricultural work itself, toluene, pesticides, heavy metal or dust exposure, work with farm animals, and nicotine exposure from plants. Of these, pesticides are the most highly studied. The majority of qualifying studies were epidemiological studies. Nigral striatal regions were the most well studied brain area impacted. Of the three human neuroimaging studies we found, two focused on functional networks and the third focused on gray matter. We identified two major directions for future studies that will help inform preventative strategies for brain health in vulnerable agricultural workers: (1) the effects of moderators such as type of work, sex, migrant status, race, and age; and (2) more comprehensive brain imaging studies, both observational and experimental, involving several imaging techniques.

Role of land use and land cover in residential exposures to agricultural pesticide models

Exposure of the general population to pesticides, especially in agricultural areas, is a major public health concern. This review analyses the role of Land Use and Land Cover (LULC) in Residential Exposure to Agricultural Pesticides (REAP) and how it is measured and modelled. Some epidemiological studies have shown that basic LULC variables, such as distance to a crop and field size, are relevant for explaining REAP. However, the potential of LULC mitigation elements, such as vegetation barriers, grassy strips and buffer zones, to mitigate REAP has been poorly studied. The availability of recent low-cost and high-quality geospatial data enables REAP models to include alternative and more precise LULC variables. This review also highlights the need for (i) generic environmental sampling protocols, (ii) exposure and spraying datasets and (iii) assessment of the mitigation capacity of LULC to improve REAP modelling significantly.

The relationship between pesticide exposure during critical neurodevelopment and autism spectrum disorder: A narrative review

Agricultural pesticides have been one of the most extensively used compounds throughout the world. The main sources of contamination for humans are dietary intake and occupational exposure. The impairments caused by agricultural pesticide exposure have been a significant global public health problem. Recent studies have shown that low-level agricultural pesticide exposure during the critical period of neurodevelopment (pregnancy and lactation) is closely related to autism spectrum disorder (ASD). Inhibition of acetylcholinesterase, gut microbiota, neural dendrite morphology, synaptic function, and glial cells are targets for the effects of pesticides during nervous system development. In the present review, we summarize the associations between several highly used and frequently studied pesticides (e.g., glyphosate, chlorpyrifos, pyrethroids, and avermectins) and ASD. We also discusse future epidemiological and toxicological research directions on the relationship between pesticides and ASD.

Sex-specific acute and chronic neurotoxicity of acute diisopropylfluorophosphate (DFP)-intoxication in juvenile Sprague-Dawley rats

Preclinical efforts to improve medical countermeasures against organophosphate (OP) chemical threat agents have largely focused on adult male models. However, age and sex have been shown to influence the neurotoxicity of repeated low-level OP exposure. Therefore, to determine the influence of sex and age on outcomes associated with acute OP intoxication, postnatal day 28 Sprague-Dawley male and female rats were exposed to the OP diisopropylfluorophosphate (DFP; 3.4 mg/kg, s.c.) or an equal volume of vehicle (∼80 µL saline, s.c.) followed by atropine sulfate (0.1 mg/kg, i.m.) and pralidoxime (2-PAM; 25 mg/kg, i.m.). Seizure activity was assessed during the first 4 h post-exposure using behavioral criteria and electroencephalographic (EEG) recordings. At 1 d post-exposure, acetylcholinesterase (AChE) activity was measured in cortical tissue, and at 1, 7, and 28 d post-exposure, brains were collected for neuropathologic analyses. At 1 month post-DFP, animals were analyzed for motor ability, learning and memory, and hippocampal neurogenesis. Acute DFP intoxication triggered more severe seizure behavior in males than females, which was supported by EEG recordings. DFP caused significant neurodegeneration and persistent microglial activation in numerous brain regions of both sexes, but astrogliosis occurred earlier and was more severe in males compared to females. DFP males and females exhibited pronounced memory deficits relative to sex-matched controls. In contrast, acute DFP intoxication altered hippocampal neurogenesis in males, but not females. These findings demonstrate that acute DFP intoxication triggers seizures in juvenile rats of both sexes, but the seizure severity varies by sex. Some, but not all, chronic neurotoxic outcomes also varied by sex. The spatiotemporal patterns of neurological damage suggest that microglial activation may be a more important factor than astrogliosis or altered neurogenesis in the pathogenesis of cognitive deficits in juvenile rats acutely intoxicated with OPs.

Pesticides and risk assessment in Shanghai fruit and raw eaten vegetables

A database of 392 pesticides established by an Ultrahigh performance liquid chromatography-tandem Q/Orbitrap high-resolution mass spectrometer (UPLC-Q/Orbitrap-HRMS) was used to screen multiple residues of pesticides in fruit and raw eaten vegetables from planting farms in Shanghai. Risk assessment was conducted with the screened results of the determined pesticides as to evaluate food safety. In 95% of the samples, one or more pesticides had a content below the maximum residue limits (MRLs) as set in the national Chinese standard. The co-occurrence of multi-residues of pesticides was more severe in peach and muskmelon, when compared with other food. All hazard index values of different groups were in the range of 0.19% to 12.3%, demonstrating that chronic dietary risk of studied fruits and raw eaten vegetables is low and the studied food samples were safe for human consumption in terms of these detected pesticides.

Endocrine disruptor global policy

Over the past several decades, scientific consensus has grown around the concept and evidence for human health impacts from exposure to endocrine disrupting chemicals (EDCs). A series of publications have now demonstrated considerable economic costs of EDC exposure-induced adverse health outcomes. This research has suggested economic burdens in the hundreds of billions, even considering only a small subset of EDCs and health. As of yet, regulatory efforts and policies to protect and decrease human exposure to most EDCs have been insufficient and have not kept pace with the science. Given the overwhelming scientific evidence, referenced throughout this collection, as well as the economic costs of inaction, described here, regulations are clearly needed. The EU and some other countries have taken promising steps towards protective regulation of EDCs, though the response of the US and many other countries has been limited or altogether lacking. Regulatory bodies that have and continue to apply risk-based approaches to regulating EDCs have also failed to consider the complete economic impacts of EDC-related health impacts. In this chapter, we will discuss broad strategies taken to regulate EDCs, examine the approaches currently taken to regulate EDCs in a global context (discussing the strengths and weaknesses of these regulations), discuss the economic costs of EDC exposures (detailing where consideration of health and economic costs could improve regulations), and discuss next steps and novel approaches to adapting existing regulatory frameworks to this class of chemicals.

Agrochemical pesticide production, trade, and hazard: Narrowing the information gap in Colombia

Pesticides are a major tool for the intensification of agriculture, and helped to increase food, feed and biofuel production. Yet, there are persistent concerns about the negative effects of pesticides in human health and the environment, particularly in low and middle income countries (LMICs). Given the lack of information on pesticide exposure and hazard, Colombia exemplifies the need to narrow the information gap on pesticide risk in LMICs. We assessed pesticide hazard in Colombia based on the official toxicity categorization, compared it to more integral international standards, and identified main actions to narrow this information gap. Results showed that Colombia has been a relevant regional actor in pesticide production and trade, reaching almost 75 million kilogrammes and liters sold in 2016. Based on acute toxicity for humans, a quarter of the amount of pesticides sales and imports, and a third of the exports in 2016 ranged from moderately to extremenly toxic. The top-selling agrochemicals in 2016 (glyphosate with 14% of the total sales, chlorpyrifos 7.5% and mancozeb 6.9%) are also commonly used in other countries, reflecting a homogenized global industry. Compared to integral international categorizations, we found that for that year 63% of the pesticides sold with slightly acute toxicity are actually considered highly hazardous pesticides (HHP) for humans or the environment, evidencing the need to use a more integral hazard categorization in the country. Narrowing the information gap in pesticide use and associated risks demands a transparent process of knowledge creation and sharing, including funtional information and monitoring systems. This should be part of an integral assessment and regulation that better defines HHP, their production and trade to reduce pesticide risk while informing a transition towards sustainable food systems.

Pesticide residues and health risk appraisal of tomato cultivated in greenhouse from the Mediterranean region of Turkey

This research aims at assessing the health risks associated with pesticide residues in greenhouse grown tomato production in the Mediterranean Region of Turkey. A multiresidue method based on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) was used for sample preparation that is applied for pesticide detection from extraction of tomato samples in the methodology generated by The Association of Official Analytical Chemists (AOAC) Official Method. The restrain of the quantification varied from 0.002 to 0.009 mg kg-1. The validated data exposed both adequate recoveries, repeatability and reproducibility, including accomplished all other requirements of the European DG SANTE/12682/2019 Guideline. This study divulges that tomatoes cultivated in greenhouse demonstrate 61.5% of samples with one or various pesticide residues. The maximum permitted residue level of above the EU DG Guideline was in 12.2% of the samples. The main determined pesticide residues on the tomatoes cultivated in greenhouse were identified as chlorpyrifos methyl, cyfluthrin, deltamethrin, and acetamiprid. Chlorpyrifos methyl (9.5%), cyfluthrin (6.6%), deltamethrin (5.5%), and acetamiprid (3.2%) were recognized as the most conducing residues to the hazard index (HI). The HI was 9.5% for adults and 11.02% for children (3 to <10 years). The major contributor of the HI was chlorpyrifos in both.

Relation between organophosphate pesticide metabolite concentrations with pesticide exposures, socio-economic factors and lifestyles: A cross-sectional study among school boys in the rural Western Cape, South Africa

Evidence on the relationship between lifestyle, socio-economic factors and pesticide exposure and urinary concentrations of organophosphate (OP) pesticide metabolites among children is generally incomplete. This study investigated the relationship between socio-economic factors and reported pesticide exposures and the sum of three urinary concentrations of dialkyl phosphate metabolites (DAP) among boys living in the rural areas of the Western Cape, South Africa. Data was collected during a cross-sectional study of 183 boys from three agricultural intense areas. Measurements included a questionnaire on socio-economic and pesticide exposures and urinary DAP concentrations. Most boys (70%) lived on farms with a median age of 12 years (range: 5.0-19.5 years). Children aged >14 years had lower DAP urine concentrations (median = 39.9 ng/ml; β = -68.1 ng/ml; 95% CI: -136.8, 0.6) than children aged 9 years and younger (median = 107.0 ng/ml). DAP concentrations also varied significantly with area, with concentrations in the grape farming area, Hex River Valley (median = 61.8 ng/ml; β = -52.1; 95% CI: -97.9, -6.3 ng/ml) and the wheat farming area, Piketberg (median = 72.4 ng/ml; β = -54.2; 95% CI: 98.8, -9.7 ng/ml) lower than those in the pome farming area, Grabouw (median = 79.9 ng/ml). Other weaker and non-significant associations with increased DAP levels were found with increased household income, member of household working with pesticides, living on a farm, drinking water from an open water source and eating crops from the vineyard and or garden. The study found younger age and living in and around apple and grape farms to be associated with increased urinary DAP concentrations. Additionally, there were other pesticide exposures and socio-economic and lifestyle factors that were weakly associated with elevated urinary DAP levels requiring further study. The study provided more evidence on factors associated to urinary DAP concentrations especially in developing country settings.