Pesticide exposure and neurodevelopment in children aged 6-9 years from Talamanca, Costa Rica

Biomonitoring urinary pesticide metabolites in preschool children by supported liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry and their association with oxidative stress

Investigating pesticide exposure and oxidative stress in preschool children is essential for elucidating the determinants of environmental health in early life, with human biomonitoring of urinary pesticide metabolites serving as a critical strategy for achieving this objective. This study demonstrated biomonitoring of 2 phenoxyacetic acid herbicides, 2 organophosphorus pesticide metabolites, and 4 pyrethroid pesticide metabolites in 159 preschool children and evaluated their association with oxidative stress biomarker 8-hydroxydeoxyguanosine. An enzymatic deconjugation process was used to release urinary pesticide metabolites, which were then extracted and enriched by supported liquid extraction, and quantified by ultra-high performance liquid chromatography-tandem mass spectrometry with internal standard calibration. Dichloromethane: methyl tert‑butyl ether (1:1, v/v) was optimized as the solvent for supported liquid extraction, and we validated the method for linear range, recovery, matrix effect and method detection limit. Method detection limit of the pesticide metabolites ranged from 0.01 μg/L to 0.04 μg/L, with satisfactory recoveries ranging from 70.5 % to 95.5 %. 2,4,5-Trichlorophenoxyacetic acid was not detected, whereas the other seven pesticide metabolites were detected with frequencies ranging from 10.1 % to 100 %. The concentration of urinary pesticide metabolites did not significantly differ between boys and girls, with the median concentrations being 9.39 μg/L for boys and 4.90 μg/L for girls, respectively. Spearman correlation analysis indicated that significant positive correlations among urinary metabolites. Bayesian kernel machine regression revealed a significant positive association between urinary pesticide metabolites and 8-hydroxydeoxyguanosine. Para-nitrophenol was the pesticide metabolite that contributed significantly to the elevated level of oxidative stress.

Neurodevelopmental assessments used to measure preschoolers' cognitive development in Latin America: a systematic review

OBJECTIVE

The objective of this study was to systematically review the standardized neurodevelopmental assessments used to study preschool-aged children's cognitive development in Spanish-speaking Latin America.

METHODS

The authors systematically searched PubMed, PsycINFO, and ERIC databases for peer-reviewed articles from Spanish-speaking Latin American countries. Articles were included if they measured cognitive development among children aged 2-6 years using at least one standardized assessment tool; 97 articles were included and reviewed in accordance with PRISMA guidelines to assess their use of these tools.

RESULTS

Ninety-seven studies across 13 countries used a total of 41 assessments to measure cognitive development; most widely used were the Wechsler intelligence scales (n = 46/97), particularly the Wechsler Preschool and Primary Scale of Intelligence and Wechsler Intelligence Scale for Children (n = 23 and 29, respectively). Other common assessments included the McCarthy Scales of Children's Abilities (n = 9), Raven's Progressive Matrices (n = 9), Child Neuropsychological Assessment (n = 8), and Peabody Picture Vocabulary Test (n = 7). In regions where normative data for a given assessment were unpublished, authors commonly used norms from the United States, Mexico, or Spain or did not report standard scores in their analyses.

CONCLUSIONS

The wide range of tools used in these studies presents a challenge for generalizing results when measuring the neurodevelopment of Latin American preschool-aged children. The low availability of normative data for specific regions reveals concerns if some tools are culturally and linguistically appropriate even when Spanish is a common language, particularly in low-resource settings. Future work to forge greater consistency in the use of validated measures, clarity in reporting research methods, and publication of regional normative data would benefit the field.

Prenatal current-use pesticide exposure and children's neurodevelopment at one year of age in the Infants' Environmental Health (ISA) birth cohort, Costa Rica

BACKGROUND

Pesticide exposure may affect young children's neurodevelopment, but only few cohort studies have addressed possible effects of non-organophosphate pesticides.

OBJECTIVE

We evaluated associations between prenatal current-use pesticide exposure and neurodevelopmental outcomes among 1-year-old children from the Infants' Environmental Health (ISA) birth cohort.

METHODS

To determine prenatal pesticide exposure, we measured biomarkers of pyrimethanil, chlorpyrifos, synthetic pyrethroids, and 2,4-D in urine samples among 355 women, 1-3 times during pregnancy. One-year post-partum, we evaluated children's neurodevelopment with the Bayley Scales of Infant and Toddler Development 3rd edition (BSID-III). We assessed associations between exposures and neurodevelopmental outcomes (composite and z-scores) using single-chemical linear regression models adjusted for possible confounders (maternal education, parity, sex, gestational age at birth, child age, HOME-score, location of assessment, biomarkers of mancozeb), and studied effect-modification by sex. We evaluated non-linear associations of multiple pesticide exposures with Bayesian kernel machine regression (BKMR).

RESULTS

We found higher prenatal urinary 2,4-D concentrations were associated with lower language (βper ten-fold increase = -2.0, 95 % confidence interval (CI) = -3.5, -0.5) and motor (βper ten-fold increase = -2.2, 95 %CI = -4.2, -0.1) composite scores among all children. Also, higher chlorpyrifos exposure [measured as urinary 3,5,6-trichloro-2-pyridinol (TCPy)] was associated with lower cognitive composite scores (βper ten-fold increase = -1.9, 95 %CI = -4.7, 0.8), and lower motor composite scores among boys (βper ten-fold increase = -3.8, 95 % CI = -7.7, 0.1) but not girls (βper ten-fold increase = 2.3, 95 %CI = -1.6, 6.3, pINT = 0.11). Finally, higher pyrimethanil was associated with lower language abilities among girls, but not boys. Pyrethroid metabolite concentrations did not explain variability in BSID-III composite scores. Associations were similar for BSID-III z-scores, and we found no evidence for non-linear associations or mixture effects.

DISCUSSION

Prenatal exposure to common-use pesticides may affect children's neurodevelopment at 1-year of age, some effects may be sex-specific.

Depressive symptoms and suicide attempts among farmers exposed to pesticides

Pesticides safeguard crop health but may diminish cholinesterase activity in farmers, potentially leading to psychiatric disorders like depression and suicide attempts. This study, with 453 participants (225 pesticide-exposed farmers, 228 non-farmers) in Almería, Spain, aimed to investigate the presence of depressive symptoms and suicide attempts, the decrease acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity, and their relationship with pesticide exposure in farmers. Depressive symptoms were evaluated using the Spanish adaptation of the Beck Depression Inventory, and blood samples were analyzed for AChE and BChE activity. Farmers showed significantly increased risk of moderate/severe depression and suicide attempts compared to non-farmers (OR = 2.18; p = 0.001), with highest risks observed among mancozeb users (OR = 2.76; p = 0.001 for depression) and malathion users (OR = 3.50; p = 0.001 for suicide attempts). Findings emphasize elevated depression and suicide risks among pesticide-exposed farmers, particularly associated with chlorpyrifos, mancozeb, and malathion exposure.

Organophosphorus pesticide exposure from house dust and parent-reported child behavior in Latino children from an orchard community

BACKGROUND

Organophosphorus pesticide (OP) exposure is known to have adverse effects on the nervous system. Children from agricultural communities are at risk of exposure to these chemicals from their indoor environments that can lead to neurological and developmental problems, including changes in behavior.

OBJECTIVE

The aim of this study is to evaluate whether the take-home pathway exposure is associated with behavioral and emotional problems in Latino Orchid Community children.

METHOD

The study was implemented over a period of two years (2008-2010) in an orchard farming community with a total of 324 parents who had children between the ages of 5-12 years old. Mothers of the children were asked to complete the Child Behavior Checklist (CBCL) and dust from their carpets was collected. Emotional and behavioral deficits were assessed based on the CBCL and house dust was assessed for OP concentrations. In this study, correlations between OPs in house dust and CBCL subscales were estimated using linear regression models with total OP concentrations classified by tertiles. This study also facilitated the comparison between the agricultural and non-agricultural families in terms of behavioral deficits and house dust concentrations of pesticides.

RESULTS

The data from the study shows that there was a positive association between the concentration of OP residues in house dust and internalizing behavior (β=2.06, p=0.05) whereas the association with externalizing behavior was not significant after accounting for sociocultural covariates. Significant positive associations of OP residues with somatic problems (p=0.02) and thought problems (p=0.05) were also found.

CONCLUSION

The data support a potential role of OP exposure in childhood development, with a specific focus on internalizing behavior. Future work focused on longitudinal studies may uncover the long-term consequences of OP exposure and behavior.

The research landscape concerning environmental factors in neurodevelopmental disorders: Endocrine disrupters and pesticides-A review

In recent years, environmental epidemiology and toxicology have seen a growing interest in the environmental factors that contribute to the increased prevalence of neurodevelopmental disorders, with the purpose of establishing appropriate prevention strategies. A literature review was performed, and 192 articles covering the topic of endocrine disruptors and neurodevelopmental disorders were found, focusing on polychlorinated biphenyls, polybrominated diphenyl ethers, bisphenol A, and pesticides. This study contributes to analyzing their effect on the molecular mechanism in maternal and infant thyroid function, essential for infant neurodevelopment, and whose alteration has been associated with various neurodevelopmental disorders. The results provide scientific evidence of the association that exists between the environmental neurotoxins and various neurodevelopmental disorders. In addition, other possible molecular mechanisms by which pesticides and endocrine disruptors may be associated with neurodevelopmental disorders are being discussed.

Exposure to organophosphate, pyrethroid, and neonicotinoid insecticides and dyslexia: Association with oxidative stress

Organophosphates (OPPs), pyrethroids (PYRs), and neonicotinoids (NNIs) are three major classes of insecticides used worldwide. They might compromise child neurodevelopment. However, few studies have explored the association between exposure to them and dyslexia. The present study aimed to investigate the association between dyslexia and exposure to the three classes of insecticides, as well as explore the potential role of oxidative stress in the association. A total of 355 dyslexic children and 390 controls were included in this study. The exposure biomarkers were determined by liquid chromatography-tandem mass spectrometry. Specifically, the exposure biomarkers included three typical metabolites of OPPs, three of PYRs, and nine of NNIs. Additionally, three typical oxidative stress biomarkers, namely, 8-hydroxy-2'-deoxyguanosine (8-OHdG) for DNA damage, 8-hydroxyguanosine (8-OHG) for RNA damage, and 4-hydroxy-2-nonenal-mercapturic acid (HNEMA) for lipid peroxidation were measured. The detection frequencies of the urinary biomarkers ranged from 83.9% to 100%. Among the target metabolites of the insecticides, a significant association was observed between urinary 3,5,6-trichloro-2-pyridinol (TCPy, the metabolite of chlorpyrifos, an OPP insecticide) and dyslexia. After adjusting for potential confounding variables, children in the highest quartile of TCPy levels had an increased odds of dyslexia (odds ratio [OR], 1.68; 95% confidence interval [CI]: 1.03, 2.75] in comparison to those in the lowest quartile. Among the three oxidative stress biomarkers, urinary HNEMA concentration showed a significant relationship with dyslexia. Children in the highest quartile of HNEMA levels demonstrated an increased dyslexic odds in comparison to those in the lowest quartile after multiple adjustments (OR, 1.64; 95% CI: 1.01, 2.65). Mediation analysis indicated a significant effect of HNEMA in the association between urinary TCPy and dyslexia, with an estimate of 17.2% (P < 0.01). In conclusion, this study suggested the association between urinary TCPy and dyslexia. The association could be attributed to lipid peroxidation partially.

Molecular Docking Analysis at the Human α7-nAChR and Proliferative and Evoked-Calcium Changes in SH-SY5Y Cells by Imidacloprid and Acetamiprid Insecticides

Acetamiprid (ACE) and Imidacloprid (IMI) are widely-used neonicotinoid insecticides (NNIs) with functional activity at human acetylcholine nicotinic receptors and, therefore, with putative toxic effects. The objective of this study was the evaluation of the interactions between NNIs and α7-nAChR, as this receptor keeps intracellular Ca2+ ([Ca2+]i) to an optimum for an adequate neuronal functioning. Possible interactions between NNIs and the cryo-EM structure of the human α-7 nAChR were identified by molecular docking. Additionally, NNI effects were analyzed in neuroblastoma SH-SY5Y cells, as they naturally express α-7 nAChRs. Functional studies included proliferative/cytotoxic effects (MTT test) in undifferentiated SH-SY-5Y cells and indirect measurements of [Ca2+]i transients in retinoic acid-differentiated SH-SY-5Y cells loaded with Fluo-4 AM. Docking analysis showed that the binding of IMI and ACE occurred at the same aromatic cage that the specific α-7 nAChR agonist EVP-6124. IMI showed a better docking strength than ACE. According to the MTT assays, low doses (10-50 µM) of IMI better than ACE stimulated neuroblastoma cell proliferation. At higher doses (250-500 µM), IMI also prevailed over ACE and dose-dependently triggered more abrupt fluorescence changes due to [Ca2+]i mobilization in differentiated SH-SY5Y neurons. Indeed, only IMI blunted nicotine-evoked intracellular fluorescence stimulation (i.e., nicotine cross-desensitization). Summarizing, IMI demonstrated a superior docking strength and more robust cellular responses compared to ACE, which were likely associated with a stronger activity at α-7nAChRs. Through the interaction with α-7nAChRs, IMI would demonstrate its high neurotoxic potential for humans. More research is needed for investigating the proliferative effects of IMI in neuroblastoma cells.

Fungicides as a risk factor for the development of neurological diseases and disorders in humans: a systematic review

Although studies show that pesticides, especially insecticides, may be toxic to humans, publications on the neurological effects of fungicides are scarce. As fungicides are used widely in Brazil, it is necessary to gather evidence to support actions aimed at safely using of these chemicals. We investigated through a systematic review of publications on the use of fungicides and consequences of exposure related to nervous system diseases or neurological disorders in humans. The protocol review was registered on PROSPERO and followed the guidelines of the PRISMA-Statement. As far as it is known, there is no apparent systematic review in the literature on this topic. The search was comprised of the following databases: PubMed; Web of Science; Scopus and EMBASE, using groups of Mesh terms and strategies specific to each database. Thirteen articles were selected for this review. Regarding the substances analyzed in the studies, some reported the use of fungicides in general, without separating them by type, while others summarized the categories of all pesticides by their function (insecticides, herbicides, fungicides, etc.) or chemical class (dithiocarbamate, dicarboximide, inorganic, etc.). However, most of the articles referred to fungicides that contain the metal manganese (Mn) in their composition. As for neurological disorders, articles addressed Parkinson's disease (PD), neurodevelopmental outcomes, extrapyramidal syndrome resembling PD, cognitive disorders, depression, neural tube defects, motor neurone disease, and amyotrophic lateral sclerosis. Most investigations pointed to exposure to fungicides, mainly maneb and mancozeb, leading to the development of at least one neurological disease, which suggests the need for further multicentric clinical trials and prospective studies for greater clarity of the research problem.

Indicators of occupational pesticide exposure are associated with psychiatric symptoms

In southeastern Spain, intensive and highly productive agriculture under plastic also poses a risk to human health, as evidenced by reports on acute pesticide poisoning and its effects on mental health. However, knowledge of chronic exposures and their relationship to psychiatric disorders is still limited. This study analyzed the relationship between occupational exposure to pesticides and psychiatric disorders in farmers from Almería. A cross-sectional study was conducted amongst a coastal population in Almería, where over 32,800 ha of land are dedicated to intensive agriculture in plastic greenhouses. A total of 409 people participated in the study: 203 farmers and 206 control subjects. The highest risk of psychiatric disorders was observed in farmers living in areas of high exposure to pesticides, working in greenhouses (intensive agriculture), without protective goggles and without wearing masks. This study supports previous evidence of an elevated risk of psychiatric disorders among farm workers exposed to pesticides.

Exposure to the environmentally relevant fungicide Maneb: Studying toxicity in the soil nematode Caenorhabditis elegans

Maneb is a manganese-containing ethylene bisdithiocarbamate fungicide and is still commonly used as no cases of resistance have been documented. However, studies have shown that Maneb exposure has neurodegenerative potential in mammals, resulting in symptoms affecting the motor system. Despite its extensive use, structural elucidation of Maneb has only recently been accomplished by our group. This study aimed to examine the bioavailability of Maneb, the quantification of oxidative stress-related endpoints and neurotransmitters employing pure Maneb, its metabolites and structural analogues, in the model organism Caenorhabditis elegans. Exposure to Maneb did not increase the bioavailability of Mn compared to manganese chloride, although Maneb was about 8 times more toxic with regard to lethality. Maneb generated not significantly reactive oxygen and nitrogen species (RONS) but decreased the ATP level while increasing the amount of glutathione and its oxidized form in a dose-dependent manner. Nevertheless, an alteration in the neurotransmitter homeostasis of dopamine, acetylcholine, and gamma-butyric acid (GABA) was observed as well as morphological changes in the dopaminergic neurons upon Maneb exposure, which underlines the assumption of the neurotoxic potential of Maneb. This study showed that Maneb exhibits effects based on a combined interaction of the ligand and manganese.

The susceptibility of humans to neurodegenerative and neurodevelopmental toxicities caused by organophosphorus pesticides

The toxicology field is concerned with the impact of organophosphorus (OP) compounds on human health. These compounds have been linked to an increased risk of neurological disorders, including neurodegenerative and neurodevelopmental diseases. This article aims to review studies on the role of OP compounds in developing these neurological disorders and explore how genetic variations can affect susceptibility to the neurotoxicity of these pesticides. Studies have shown that exposure to OP compounds can lead to the development of various neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), attention deficit hyperactivity disorder (ADHD), autism, intellectual disability, and other developmental neurotoxicities. Apart from inhibiting the cholinesterase enzyme, OP compounds are believed to cause other pathological mechanisms at both the extracellular level (cholinergic, serotonergic, dopaminergic, glutamatergic, and GABAergic synapses) and the intracellular level (oxidative stress, mitochondrial dysfunction, inflammation, autophagy, and apoptosis) that contribute to these disorders. Specific genetic polymorphisms, including PON1, ABCB1, NOS, DRD4, GST, CYP, and APOE, have increased the risk of developing OP-related neurological disorders.

Frequency of urinary pesticides in children: a scoping review

Pesticides are any mix of ingredients and substances used to eliminate or control unwanted vegetable or animal species recognized as plagues. Its use has been discussed in research due to the scarcity of strong scientific evidence about its health effects. International literature is still insufficient to establish a global recommendation through public policy. This study aims to explore international evidence of the presence of pesticides in urine samples from children and their effects on health through a scoping review based on the methodology described by Arksey and O'Malley. The number of articles resulting from the keyword combination was 454, and a total of 93 manuscripts were included in the results and 22 were complementary. Keywords included in the search were: urinary, pesticide, children, and childhood. Children are exposed to pesticide residues through a fruit and vegetable intake environment and household insecticide use. Behavioral effects of neural damage, diabetes, obesity, and pulmonary function are health outcomes for children that are commonly studied. Gas and liquid chromatography-tandem mass spectrometry methods are used predominantly for metabolite-pesticide detection in urine samples. Dialkylphosphates (DAP) are common in organophosphate (OP) metabolite studies. First-morning spot samples are recommended to most accurately characterize OP dose in children. International evidence in PubMed supports that organic diets in children are successful interventions that decrease the urinary levels of pesticides. Several urinary pesticide studies were found throughout the world's population. However, there is a knowledge gap that is important to address (public policy), due to farming activities that are predominant in these territories.

Locomotion and brain gene expression exhibit sex-specific non-monotonic dose-response to HFPO-DA during Drosophila melanogaster lifespan

BACKGROUND

Legacy per- and polyfluoroalkyl substances (PFAS), known for their environmental persistence and bio-accumulative properties, have been phased out in the U.S. due to public health concerns. A newer polymerization aid used in the manufacture of some fluoropolymers, hexafluoropropylene oxide-dimer acid (HFPO-DA), has lower reported bioaccumulation and toxicity, but is a potential neurotoxicant implicated in dopaminergic neurodegeneration.

OBJECTIVE

We investigated HFPO-DA's bio-accumulative potential and sex-specific effects on lifespan, locomotion, and brain gene expression in fruit flies.

METHODS

We quantified bioaccumulation of HFPO-DA in fruit flies exposed to 8.7×10⁴µg/L of HFPO-DA in the fly media for 14 days via UHPLC-MS. Long-term effect on lifespan was determined by exposing both sexes to 8.7×10² - 8.7×10⁵µg/L of HFPO-DA in media. Locomotion was measured following 3, 7, and 14 days of exposures at 8.7×10¹ - 8.7×10⁵µg/L of HFPO-DA in media, and high-throughput 3'-end RNA-sequencing was used to quantify gene expression in fly brains across the same time points.

RESULTS

Bioaccumulation of HFPO-DA in fruit flies was not detected. HFPO-DA-induced effects on lifespan, locomotion, and brain gene expression, and lowest adverse effect level (LOAEL) showed sexually dimorphic patterns. Locomotion scores significantly decreased in at least one dose at all time points for females and only at 3-day exposure for males, while brain gene expression exhibited non-monotonic dose-response. Differentially expressed genes correlated to locomotion scores revealed sex-specific numbers of positively and negatively correlated genes per functional category.

CONCLUSION

Although HFPO-DA effects on locomotion and survival were significant at doses higher than the US EPA reference dose, the brain transcriptomic profiling reveals sex-specific changes and neurological molecular targets; gene enrichments highlight disproportionately affected categories, including immune response: female-specific co-upregulation suggests potential neuroinflammation. Consistent sex-specific exposure effects necessitate blocking for sex in experimental design during HFPO-DA risk assessment.

Exposure to non-persistent pesticides and sexual maturation of Spanish adolescent males

BACKGROUND

Several non-persistent pesticides are endocrine disrupting chemicals and may impact on sexual maturation.

OBJECTIVE

To examine the association between urinary biomarkers of non-persistent pesticides and sexual maturation in adolescent males in the Environment and Childhood (INMA) Project.

METHODS

The metabolites of several pesticides were measured in spot urine samples collected from 201 boys aged 14-17 years, including: 3,5,6-trichloro-2-pyridinol (TCPy), metabolite of chlorpyrifos; 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPy), metabolite of diazinon; malathion diacid (MDA), metabolite of malathion; diethyl thiophosphate (DETP) and diethyl dithiophosphate, non-specific metabolites of organophosphates; 3-phenoxybenzoic acid (3-PBA) and dimethyl cyclopropane carboxylic acid, metabolites of pyrethroids; 1-naphthol (1-NPL), metabolite of carbaryl; and ethylene thiourea (ETU), metabolite of dithiocarbamate fungicides. Sexual maturation was assessed using Tanner stages, self-reported Pubertal Development Scale, and testicular volume (TV). Multivariate logistic regression was employed to examine associations between urinary pesticide metabolites and the odds of being in Tanner stage 5 of genital development (G5) or pubic hair growth (PH5); stage ≥4 of overall pubertal development, gonadarche, and adrenarche; or having mature TV (≥25 mL).

RESULTS

DETP concentrations>75th percentile (P75) were associated with lower odds of being in stage G5 (OR = 0.27; 95% CI = 0.10-0.70), detectable TCPy with lower odds of gonadal stage≥4 (OR = 0.50; 95% CI = 0.26-0.96), and intermediate detectable MDA concentrations (<P75) with lower odds of adrenal stage≥4 (OR = 0.32; 95% CI = 0.11-0.94). Conversely, detectable concentrations of 1-NPL were associated with higher odds of adrenal stage≥4 (OR = 2.61; 95% CI = 1.30-5.24) but lower odds of mature TV (OR = 0.42; 95% CI = 0.19-0.90).

CONCLUSION

Exposure to certain pesticides may be associated with delayed sexual maturity in adolescent males.

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.

Neurocytotoxicity of imidacloprid- and acetamiprid-based comercial insecticides over the differentiation of SH-SY5Y neuroblastoma cells

Neonicotinoids are effective insecticides with specificity for invertebrate nicotinic acetylcholine receptors. Neonicotinoids are chemically stable and tend to remain in the environment for long so concerns about their neurotoxicity in humans do nothing but increase. Herein, we evaluated the chronic toxic effects of acetamiprid- and imidacloprid-based insecticides over the differentiation of human neuroblastoma SH-SY5Y cells, which were exposed to these insecticides at a concentration range similar to that applied to crop fields (0.01-0.5 mM). Both insecticides did not have acute cytotoxic effects in both non-differentiated and in staurosporine-differentiated SH-SY5Y cells cytotoxicity as measured by the MTT and vital-dye exclusion tests. However, after a chronic (7-day) treatment, only imidacloprid dose-dependently decreased the viability of SH-SY5Y cells (F(4,39) = 43.05, P < 0.001), largely when administered-during cell differentiation (F(4,39) = 51.86, P < 0.001). A well-defined dose-response curve was constructed for imidacloprid on day 4 (R² = 0.945, EC₅₀ = 0.14 mM). During differentiation, either imidacloprid or acetamiprid dose-dependently caused neurite branch retraction on day 3, likely because of oxidative stress, to the extent that cells turned into spheres without neurites after 7-day treatment. Despite their apparent safety, the neurodevelopmental vulnerability of SH-SY5Y neurons to the chronic exposure to imidacloprid and to a lesser extent to acetamiprid points to a neurotoxic risk for humans.

Kisspeptin as potential biomarker of environmental chemical mixture effect on reproductive hormone profile: A pilot study in adolescent males

BACKGROUND

Kisspeptin has been proposed as an effect biomarker to understand the mechanisms by which some environmental chemicals adversely affect the human reproductive system.

OBJECTIVE

To ascertain whether kisspeptin serum protein and DNA methylation levels are associated with exposure to several environmental chemicals (individually and as a mixture) and serum reproductive hormone levels in adolescent males.

METHODS

Three phenols (bisphenol A [BPA], methyl-paraben [MPB], and benzophenone-3 [BP3]); two toxic metals (arsenic and cadmium); and four metabolites of non-persistent pesticides, including insecticides (2-isopropyl-6-methyl-4-pyrimidinol [IMPy], malathion diacid [MDA], and dimethylcyclopropane carboxylic acid [DCCA]) and fungicides (ethylene thiourea [ETU]) were measured in first-morning urine samples of 133 adolescent males aged 15-17 years from the INMA-Granada cohort. In blood samples collected on the same day, KISS1 gene DNA methylation was measured at four CpGs from the Exon IV, as well as serum levels of kiss54 protein, total testosterone (T), estradiol (E₂), sex hormone binding-globulin, dehydroepiandrosterone sulfate, luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Multiple linear regression and mixture (quantile g-computation) models were fit.

RESULTS

Urinary MDA and DCCA concentrations were associated with higher kiss54 levels [% change (95%CI) for each log-unit increase in concentration = 2.90 (0.32;5.56), and 1.93 (0.45,3.43), respectively]; IMPy with lower DNA methylation percentage at CpG1 and total CpGs [% change (95%CI) = -1.15 (-1.96;-0.33): -0.89 (-1.73;-0.01), respectively]; and BP3 and DCCA with lower total CpGs methylation [-0.53 (-1.04;-0.01) and - 0.69 (-1.37;-0.01), respectively]. The pesticide mixture and the whole chemical mixture were associated with higher kiss54 [% change (95%CI) = 9.09 (3.29;15.21) and 11.61 (3.96;19.82), respectively] and lower methylation levels at several CpGs. Additionally, serum kiss54 in the third tertile was associated with higher LH levels [% change (95%CI) = 28.69 (3.75-59.63)], and third-tertile CpG1, CpG2, and total CpG methylation percentages were associated with lower FSH and E₂.

CONCLUSION

The findings of the present study and the negative correlation between serum kiss54 levels and KISS1 DNA methylation percentages suggested that kisspeptin may be a promising effect biomarker.

Pesticide use in banana plantations in Costa Rica - A review of environmental and human exposure, effects and potential risks

Biodiversity is declining on a global scale. Especially tropical ecosystems, containing most of the planetary biodiversity, are at risk. Agricultural monocrop systems contribute to this decline as they replace original habitats and depend on extensive use of synthetic pesticides that impact ecosystems. In this review we use large-scale banana production for export purposes in Costa Rica as an example for pesticide impacts, as it is in production for over a century and uses pesticides extensively for more than fifty years. We summarise the research on pesticide exposure, effects and risks for aquatic and terrestrial environment, as well as for human health. We show that exposure to pesticides is high and relatively well-studied for aquatic systems and humans, but hardly any data are available for the terrestrial compartment including adjacent non target ecosystems such as rainforest fragments. Ecological effects are demonstrated on an organismic level for various aquatic species and processes but are not available at the population and community level. For human health studies exposure evaluation is crucial and recognised effects include various types of cancer and neurobiological dysfunctions particularly in children. With the many synthetic pesticides involved in banana production, the focus on insecticides, revealing highest aquatic risks, and partly herbicides should be extended to fungicides, which are applied aerially over larger areas. The risk assessment and regulation of pesticides so far relies on temperate models and test species and is therefore likely underestimating the risk of pesticide use in tropical ecosystems, with crops such as banana. We highlight further research approaches to improve risk assessment and, in parallel, urge to follow other strategies to reduce pesticides use and especially hazardous substances.

Pyrethroid and Chlorpyrifos Pesticide Exposure, General Intellectual Abilities, and Executive Functions of School Children from Montevideo, Uruguay

Children's developing brains are susceptible to pesticides. Less is known about the effect of exposure to chlorpyrifos and pyrethroids on executive functions (EF). We measured urinary 3,5,6-trichloro-2-pyridinol (TCPy), a metabolite of chlorpyrifos, and urinary 3-phenoxybenzoic acid (3-PBA), a general, nonspecific metabolite of pyrethroids in first-grade children from Montevideo, Uruguay (n = 241, age 80.6 ± 6.4 months, 58.1% boys). EFs were assessed with the Intra-dimensional/Extra-dimensional shift (IED), Spatial Span (SSP), and Stockings of Cambridge (SOC) tests from the Cambridge Neuropsychological Test Automated (CANTAB) Battery. General intellectual ability (GIA) was assessed using the Woodcock-Muñoz Cognitive battery. Median (range) urinary TCPy and 3-PBA levels were 16.7 (1.9, 356.9) ng/mg of creatinine and 3.3 (0.3, 110.6) ng/mg of creatinine, respectively. In multivariable generalized linear models, urinary TCPy was inversely associated with postdimensional errors on the IED task β [95% CI]: -0.11 [-0.17, -0.06]. Urinary 3-PBA was inversely associated with the total number of trials -0.07 [-0.10, -0.04], and the total number of errors -0.12 [-0.18, -0.07] on the IED task. When TCPy and 3-PBA were modeled together, the associations did not differ from single-metabolite models. We found no evidence of effect modification by blood lead level (BLL). Pesticide exposure may affect EF performance in urban children.

Changes in the gut microbiota of rats after exposure to the fungicide Mancozeb

Mancozeb is a fungicide commonly used in pest control programs, especially to protect vineyards. Its toxicity has already been evidenced in several studies. However, its influence on the composition and diversity of the gut microbiota remains unknown. In this work, the adverse impact of Mancozeb on the intestinal microbiota was investigated using a rodent model. Adult male Sprague Dawley rats were randomized into three groups: Control (standard diet), MZ1 (Mancozeb dose: 250 mg/kg bw/day), and MZ2 (Mancozeb dose: 500 mg/kg bw/day). After 12 weeks of experiment, animals were euthanized, and feces present in the intestine were collected. After fecal DNA extraction, the V4 region of the 16S rRNA gene was amplified followed by sequencing in an Ion S5™ System. Alpha and beta diversity analysis showed significant differences between Control and Mancozeb groups (MZ1 e MZ2), but no difference between MZ1 and MZ2 was observed. Seven genera significantly increased in abundance following Mancozeb exposure, while five genera decreased. Co-occurrence analyses revealed that the topological properties of the microbial networks, which can be used to infer co-occurrence interaction patterns among microorganisms, were significantly lower in both groups exposed to Mancozeb when compared to Control. In addition, 23 differentially abundant microbial metabolic pathways were identified in Mancozeb-treated groups mainly related to a change in energy metabolism, LPS biosynthesis, and nucleotide biosynthesis. In conclusion, the exposure to Mancozeb presented side effects by changing the composition of the microbiota in rats, increasing bacterial diversity regardless of the dose used, reducing the interaction patterns of the microbial communities, and changing microbial metabolic pathways.

Relationship between Butyrylcholinesterase Activity and Cognitive Ability in Workers Exposed to Chlorpyrifos

Background. The use of Chlorpyrifos leads to a public, environmental, and occupational health problem associated with adverse effects in the exposed population, generating alterations mainly in the central nervous system, such as cognitive function. This study aimed to estimate the association between butyrylcholinesterase activity (BChE) and cognitive ability in workers exposed to chlorpyrifos. Methods. We designed a cross-sectional study, where we measured BChE in serum samples as an indicator of exposure to chlorpyrifos. The cognitive ability was assessed by the mean score of the Peruvian version of the Mini-Mental State Examination (MMSE). We also used a questionary to collect demographic and occupational information. Results. We evaluated 120 farmers with a predominance of males (92%) and a mean age of 32.1 ± 9.0 years. We found most of the workers in fumigation activities (84%). The mean BChE was 6144.7 ± 2355.0 U/L, and 46% presented inhibition enzyme (<5500 U/L). The median MMSE score was 28 (interquartile range: 26.5–31.5; 6% showed an alteration in cognitive ability (score < 24)). The MMSE test found a significant association between BChE inhibition and MMSE score (β: −0.071, 95%CI: −0.108 to −0.025). Conclusion. In this study, 45.8% of workers exposed to chlorpyriphos presented BChE inhibition. The BChE inhibition is significantly associated with the MMSE score in workers exposed to chlorpyrifos.

A Comprehensive Review of Pesticide Residues in Peppers

Pesticides are chemicals that are used to control pests such as insects, fungi, and weeds. Pesticide residues can remain on crops after application. Peppers are popular and versatile foods that are valued for their flavor, nutrition, and medicinal properties. The consumption of raw or fresh peppers (bell and chili) can have important health benefits due to their high levels of vitamins, minerals, and antioxidants. Therefore, it is crucial to consider factors such as pesticide use and preparation methods to fully realize these benefits. Ensuring that the levels of pesticide residues in peppers are not harmful to human health requires rigorous and continuous monitoring. Several analytical methods, such as gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-Vis), and nuclear magnetic resonance spectroscopy (NMR), can detect and quantify pesticide residues in peppers. The choice of analytical method depends on the specific pesticide, that is being tested for and the type of sample being analyzed. The sample preparation method usually involves several processes. This includes extraction, which is used to separate the pesticides from the pepper matrix, and cleanup, which removes any interfering substances that could affect the accuracy of the analysis. Regulatory agencies or food safety organizations typically monitor pesticide residues in peppers by stipulating maximum residue limits (MRLs). Herein, we discuss various sample preparation, cleanup, and analytical techniques, as well as the dissipation patterns and application of monitoring strategies for analyzing pesticides in peppers to help safeguard against potential human health risks. From the authors' perspective, several challenges and limitations exist in the analytical approach to monitoring pesticide residues in peppers. These include the complexity of the matrix, the limited sensitivity of some analytical methods, cost and time, a lack of standard methods, and limited sample size. Furthermore, developing new analytical methods, using machine learning and artificial intelligence, promoting sustainable and organic growing practices, improving sample preparation methods, and increasing standardization could assist efficiently in analyzing pesticide residues in peppers.

Neurobehavioral Effects of Low-Dose Chronic Exposure to Insecticides: A Review

The modes of action of insecticides frequently involve a neurotoxic effect; therefore, the study of neurotoxic effects caused by long-term and low-dose insecticide exposure is of particular interest. This study looks at whether or not new studies conducted after 2009 and up to 2021 have provided new evidence for a better understanding of the actual neurobehavioral risk associated with long-term insecticide exposure. We selected and reviewed studies carried out on the neurobehavioral effects of neurotoxic insecticides (organophosphates and/or carbamates, pyrethroids, multiple or undefined insecticides, and organochlorines) considering occupational and non-occupational exposures. The articles were also scored and ranked based on seven parameters. Eighty-six studies were chosen for a final review process from among the 950 scientific papers identified. Twenty-six addressed occupational exposure and six environmental exposure. Among the latter group of studies, 17 focused on rural residents, to be assumed exposed because of living in rural areas, and 43 on the general population. Pending doubts have not been resolved in the last ten years due to the presence of contradictory and hardly comparable results and the fact that in most of the studies showing an evident neurobehavioral impairment the frequent presence of a previous episode of poisoning and hospitalization, with severe brain hypoxia, impaired the possibility of confirming the presence of a causal association with insecticide exposure. Interestingly, the most severely exposed groups, such as applicators who did not wear personal protective equipment, performed worse on neurobehavioral tests. As for residential exposure, there is sufficient evidence to suggest that prenatal OP exposure may increase the risk of ADHD in children.

Childhood exposure to non-persistent pesticides and pubertal development in Spanish girls and boys: Evidence from the INMA (Environment and Childhood) cohort

This study assessed cross-sectional associations between urinary metabolites of non-persistent pesticides and pubertal development in boys and girls from urban and rural areas in Spain and examined effect modification by body mass index (BMI). Four metabolites of insecticides (TCPy, metabolite of chlorpyrifos; IMPy, metabolite of diazinon; DETP, non-specific metabolite of organophosphates; 3-PBA, metabolite of pyrethroids) and the metabolite of ethylene-bis-dithiocarbamate fungicides (ETU) were quantified in urine collected in 2010-2016 from 7 to 11-year-old children (606 girls, 933 boys) participating in the INMA Project. Pubertal development was ascertained by Tanner stages and/or parent-reported Pubertal Development Scale (PDS). Associations between pesticide metabolites and odds of being in stage 2+ for breast development (girls), genital development (boys), pubic hair growth (girls and boys), and/or overall puberty onset, gonadarche, and adrenarche (PDS for girls and boys) were examined by mixed-effect logistic regression. Effect modification by BMI was explored by interaction terms and stratified analysis. In girls, DETP and ETU concentrations>75th percentile (P75) were associated with higher odds of overall puberty development (OR [95%CI] = 1.86 [1.07-3.24] and 1.71 [1.03-2.83], respectively, for > P75 vs. undetected concentrations), while ETU > P75 was also associated with higher odds of breast development (OR [95%CI] = 5.55 [2.83-12.91]), particularly in girls with underweight/normal weight (OR [95%CI] = 10.08 [2.62-38.76]). In boys, detection of TCPy (40%) and 3-PBA (34%) was associated with higher odds of genital development (OR [95%CI] = 1.97 [1.08-3.57] and 2.08 [1.15-3.81], respectively), and the association with 3-PBA was observed in boys with overweight/obesity alone. In addition, ETU > P75 was associated with higher odds of genital development in boys with underweight/normal weight (OR [95%CI] = 2.89 [1.08-7.74]) but higher DETP with lower odds of puberty in boys with overweight/obesity (OR [95%CI] = 0.94 [0.89-0.99] per log-unit increase in concentration). Results suggest an association of childhood exposure to ETU and certain insecticides with earlier puberty in girls and boys that may be modified by child BMI.

Respiratory and allergic outcomes among 5-year-old children exposed to pesticides

BACKGROUND

Little is known about the effects of pesticides on children's respiratory and allergic outcomes. We evaluated associations of prenatal and current pesticide exposures with respiratory and allergic outcomes in children from the Infants' Environmental Health Study in Costa Rica.

METHODS

Among 5-year-old children (n=303), we measured prenatal and current specific gravity-corrected urinary metabolite concentrations of insecticides (chlorpyrifos, pyrethroids), fungicides (mancozeb, pyrimethanil, thiabendazole) and 2,4-D. We collected information from caregivers on respiratory (ever doctor-diagnosed asthma and lower respiratory tract infections (LRTI), wheeze and cough during last 12 months) and allergic (nasal allergies, itchy rash, ever eczema) outcomes. We fitted separate multivariable logistic regression models for high (≥75th percentile (P75)) vs low (<P75) metabolite concentrations with respiratory and allergic outcomes. We also ran models including metabolite concentrations as continuous exposure variables.

RESULTS

Children's respiratory outcomes were common (39% cough, 20% wheeze, 12% asthma, 5% LRTI). High current pyrethroid metabolite concentrations (∑pyrethroids) were associated with wheeze (OR=2.37, 95% CI 1.28 to 4.34), itchy rash (OR=2.74, 95% CI 1.33 to 5.60), doctor-diagnosed asthma and LRTI. High current ethylene thiourea (ETU) (specific metabolite of mancozeb) was somewhat associated with LRTI (OR=2.09, 95% CI 0.68 to 6.02). We obtained similar results when modelling ∑pyrethroids and ETU as continuous variables. We saw inconsistent or null associations for other pesticide exposures and health outcomes.

CONCLUSIONS

Current pyrethroid exposure may affect children's respiratory and allergic health at 5 years of age. Current mancozeb exposure might contribute to LRTI. These findings are important as pyrethroids are broadly used in home environments and agriculture and mancozeb in agriculture.

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.

Reviewing the variability in urinary concentrations of non-persistent organic chemicals: evaluation across classes, sampling strategies and dilution corrections

Various biomonitoring studies have been carried out to investigate the exposure of populations by measuring non-persistent organic chemicals in urine. To accurately assess the exposure, study designs should be carefully developed to maximise reproducibility and achieve good characterization of the temporal variability. To test these parameters, the intraclass correlation coefficients (ICCs) are calculated from repeated measurements and range from poor (<0.4) to excellent (≥0.75). Several studies have reported ICCs based on diverse study designs, but an overview, including recommendations for future studies, was lacking. Therefore, this review aimed to collect studies describing ICCs of non-persistent organic chemicals, discuss variations due to study design and formulate recommendations for future studies. More than 60 studies were selected, considering various chemical classes: bisphenols, pyrethroids, parabens, phthalates, alternative plasticizers and phosphate flame retardants. The variation in ICCs for an individual chemical was high (e.g. ICC of propyl paraben = 0.28-0.91), showing the large impact of the study design and of the specific exposure sources. The highest ICCs were reported for parabens (median = 0.52), while lowest ICCs were for 3-phenoxybenzoic acid (median = 0.08) and bisphenol A (median = 0.20). Overall, chemicals that had an exposure source with high variation, such as the diet, showed lower ICCs than those with more stable exposure sources, such as indoor materials. Urine correction by specific gravity had an overall positive effect on reducing the variability of ICCs. However, this effect was mostly seen in the adult population, while specific compounds showed less variation with creatinine correction. Single samples might not accurately capture the exposure to most non-persistent organic chemicals, especially when small populations are sampled. Future studies that examine compounds with low ICCs should take adequate measures to improve accuracy, such as correcting dilution with specific gravity or collecting multiple samples for one participant.

Neurotoxicity of pesticides in the context of CNS chronic diseases

Following the introduction and application of pesticides in human life, they have always been along with health concerns both in acute poisoning and chronic toxicities. Neurotoxicity of pesticides in chronic exposures has been known as one of the most important human health problems, as most of these chemicals act through interacting with some elements of nervous system. Pesticide-induced neurotoxicity can be defined in different categories of neurological disorders including neurodegenerative (Alzheimer, Parkinson, amyotrophic lateral sclerosis, multiple sclerosis), neurodevelopmental (attention deficit hyperactivity disorder, autism spectrum disorders, developmental delay, and intellectual disability), neurobehavioral and neuropsychiatric (depression/suicide attempt, anxiety/insomnia, and cognitive impairment) disorders some of which are among the most debilitating human health problems. In this review, neurotoxicity of pesticides in the mentioned categories and sub-categories of neurological diseases have been systematically presented in relation to different route of exposures including general, occupational, environmental, prenatal, postnatal, and paternal.

A systematic review of human biomonitoring studies of 3-phenoxybenzoic acid, a urinary biomarker pyrethroid insecticide exposure, 1997 to 2019

Pyrethroid insecticides are used, for example, in agriculture, indoor environments, and mosquito control programs, resulting in human exposure. Urinary 3-phenoxybenzoic acid (3-PBA) is a nonspecific biomarker for exposure to many pyrethroids. This systematic review identified human biomonitoring studies with 3-PBA that characterize environmental pyrethroid exposures in children and adolescents, pregnant women, and adults or occupational pyrethroid exposures relative to the National Health and Nutrition Examination Survey (NHANES) populations in the United States (US). PubMed, Embase, and SciFinder were searched for "3-phenoxybenzoic acid ", CAS No. 3739-38-6, and urine or urinary or urine level. Duplicate studies and studies meeting the exclusion criteria were removed from the search results based on predetermined exclusion criteria. This screening process identified 57 papers. Twenty-one, thirteen, twenty-two, and eleven manuscripts reported urinary 3-PBA levels in children, pregnant women, environmentally exposed adults, and occupationally exposed adults, respectively. Median 3-PBA levels ranged from 0.2 to 4.7 μg/g creatinine in children (1999-2016), 0.23-1.55 μg/g creatinine in pregnant women (1997-2014), and 0.11-3.34 μg/g creatinine in environmentally exposed adults (1999-2017). 3-PBA levels in occupationally exposed adults were significantly higher than in environmentally exposed populations, ranging from 0.43 to 14 μg/g creatinine (2004-2017). 3-PBA levels in children and adults from the general North American population increased significantly with the sampling year. A decrease in 3-PBA levels was noted in the adult cohorts from PR China and Japan. 3-PBA levels in most studies appeared to be comparable to levels in the NHANES populations; however, some smaller studies had high pyrethroid exposures. Factors contributing to higher 3-PBA levels in the general population included primarily dietary exposures and residential and agricultural pyrethroid applications. These findings demonstrate that pyrethroid exposures are near-ubiquitous worldwide and, in some regions, appear to increase over time. Thus, exposures to pyrethroid insecticides represent a continuing public health concern.

Pyrethroids and developmental neurotoxicity - A critical review of epidemiological studies and supporting mechanistic evidence

BACKGROUND

Pyrethroid metabolites are widely detectable in urine from the general population, including pregnant women and children. Pyrethroids are neurotoxic and suggested endocrine disruptors. Exposure during vulnerable developmental time windows may have long-term impacts on neurodevelopment.

OBJECTIVE

To evaluate the epidemiological evidence for neurodevelopmental effects related to prenatal and childhood pyrethroid exposure in a systematic review and to assess biological plausibility by evaluating mechanistic evidence.

METHODS

We searched PubMed and Web of Science up to September 1, 2021 and included original studies published in English in which pyrethroid exposure was measured or estimated during pregnancy or childhood and associations with neurodevelopmental outcomes in the children were investigated. The Navigation Guide Systematic Review Methodology was used to evaluate the epidemiological evidence. For mechanistic evidence, we focused on relevant key events (KEs) suggested in Adverse Outcome Pathways (AOPs) using the OECD-supported AOP-wiki platform. A systematic search combining the KEs with pyrethroids, including 26 individual compounds, was performed in the ToxCast database.

RESULTS

Twenty-five epidemiological studies met the inclusion criteria, 17 presented findings on prenatal exposure, 10 on childhood exposure and two on both exposure windows. The overall body of evidence was rated as "moderate quality" with "sufficient evidence" for an association between prenatal pyrethroid exposure and adverse neurodevelopment. For childhood exposure, the overall rating was "low quality" with "limited evidence" because of cross-sectional study design. Regarding mechanistic evidence, we found that pyrethroids are able to interfere with neurodevelopmental KEs included in established AOPs for adverse neurodevelopmental. The evidence was strongest for interference with thyroid hormone (TH) function.

CONCLUSION

Pyrethroids are probably human developmental neurotoxicants and adverse impacts of pyrethroid exposure on neurodevelopment are likely at exposure levels occurring in the general population. Preventive measures to reduce exposure among pregnant women and children are warranted.

Human Exposure to Pesticides in Dust from Two Agricultural Sites in South Africa

Over the last decades, concern has arisen worldwide about the negative impacts of pesticides on the environment and human health. Exposure via dust ingestion is important for many chemicals but poorly characterized for pesticides, particularly in Africa. We investigated the spatial and temporal variations of 30 pesticides in dust and estimated the human exposure via dust ingestion, which was compared to inhalation and soil ingestion. Indoor dust samples were collected from thirty-eight households and two schools located in two agricultural regions in South Africa and were analyzed using high-performance liquid chromatography coupled to tandem mass spectrometry. We found 10 pesticides in dust, with chlorpyrifos, terbuthylazine, carbaryl, diazinon, carbendazim, and tebuconazole quantified in >50% of the samples. Over seven days, no significant temporal variations in the dust levels of individual pesticides were found. Significant spatial variations were observed for some pesticides, highlighting the importance of proximity to agricultural fields or of indoor pesticide use. For five out of the nineteen pesticides quantified in dust, air, or soil (i.e., carbendazim, chlorpyrifos, diazinon, diuron and propiconazole), human intake via dust ingestion was important (>10%) compared to inhalation or soil ingestion. Dust ingestion should therefore be considered in future human exposure assessment to pesticides.

Oxidative stress of glyphosate, AMPA and metabolites of pyrethroids and chlorpyrifos pesticides among primary school children in Cyprus

BACKGROUND

Exposure to various pesticides, such as pyrethroids and chlorpyrifos, has been previously associated with adverse effects on children's health. Scientific evidence on the human toxicity of glyphosate (GLY) and its primary metabolite, aminomethylphosphonic acid (AMPA) is limited, particularly for children. This study aimed to i) assess the exposure determinants of the studied pesticides measured in children in Cyprus, and ii) determine the association between the urinary pesticides and the biomarkers of DNA and lipid oxidative damage.

METHODS

A children's health study was set up in Cyprus (ORGANIKO study) by aligning it with the methodology and tools used in the European Human Biomonitoring Initiative (HBM4EU). Urinary GLY and AMPA, pyrethroid metabolites and the chlorpyrifos metabolite TCPy were measured in 177 children aged 10-11 years old, using mass spectrometry. Oxidative stress was assessed with 8-iso-prostaglandin F2a (8-iso-PGF2α) as a marker of lipid damage and 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a DNA oxidative damage marker, both measured with immunoassays. Questionnaires about demographic characteristics, pesticide usage, and dietary habits were filled out by the parents. Μultivariable regression models examined associations between pesticides and biomarkers of effect using two creatinine adjustments (cr1: adding it as covariate and cr2: biomarkers of exposure and effect were creatinine-adjusted).

RESULTS

Parental educational level was a significant predictor of urinary pyrethroids but not for GLY/AMPA. Median [interquartile range, IQR] values for GLY and AMPA were  0.05). Similar significant associations with 8-OHdG were shown for a pyrethroid metabolite (3-PBA) and the chlorpyrifos metabolite (TCPy). No associations were observed between the aforementioned pesticides and 8-iso-PGF2α (p > 0.05).

CONCLUSIONS

This is the first children's health dataset demonstrating the association between AMPA and DNA oxidative damage, globally. More data is needed to replicate the observed trends in other children's populations around the globe.

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.

Pyrimethanil and chlorpyrifos air concentrations and pregnant women's urinary metabolites in the Infants' Environmental Health Study (ISA), Costa Rica

BACKGROUND

Only few studies have compared environmental pesticide air concentrations with specific urinary metabolites to evaluate pathways of exposure. Therefore, we compared pyrimethanil and chlorpyrifos concentrations in air with urinary 4-hydroxypyrimethanil (OHP, metabolite of pyrimethanil) and 3,5,6-trichloro-2-pyridinol (TCPy, metabolite of chlorpyrifos) among pregnant women from the Infant's Environmental Health Study (ISA) in Matina County, Costa Rica.

METHODS

During pregnancy, we obtained repeat urinary samples from 448 women enrolled in the ISA study. We extrapolated pyrimethanil and chlorpyrifos concentrations measured with passive air samplers (PAS) (n = 48, from 12 schools), across space and time using a Bayesian spatiotemporal model. We subsequently compared these concentrationswith urinary OHP and TCPy in 915 samples from 448 women, usingseparatemixed models andconsidering several covariables.

RESULTS

A 10% increase in air pyrimethanil (ng/m3) was associated with a 5.7% (95% confidence interval (CI 4.6, 6.8) increase in OHP (μg/L). Women living further from banana plantations had lower OHP: -0.7% (95% CI -1.2, -0.3) for each 10% increase in distance (meters) as well as women who ate rice and beans ≥15 times a week -23% (95% CI -38, -4). In addition, each 1 ng/m3 increase in chlorpyrifos in air was associated with a 1.5% (95% CI 0.2, 2.8) increase in TCPy (μg/L), and women working in agriculture tended to have increased TCPy (21%, 95% CI -2, 49).

CONCLUSION

The Bayesian spatiotemporal models were useful to estimate pyrimethanil and chlorpyrifos air concentrations across space and time. Our results suggest inhalation of pyrimethanil and chlorpyrifos is a pathway of environmental exposure. PAS seems a useful technique to monitor environmental current-use pesticide exposures. For future studies, we recommend increasing the number of locations of environmental air measurements, obtaining all air and urine measurements during the same month, and, ideally, including dermal exposure estimates as well.

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.

Inhibition of Serum Esterases in Juvenile Rats Repeatedly Exposed to Low Levels of Chlorpyrifos

Chlorpyrifos (CPF) is an organophosphorus insecticide that has gained significant attention cue to the reported toxicity associated with developmental exposure. While the canonical mechanism of toxicity of CPF involves the inhibition of brain acetylcholinesterase (AChE), we have reported that exposure of juvenile rats to levels of CPF that do not yield any inhibition of brain AChE results in neurobehavioral alterations at later ages. However, it is unclear what effect exposure to these low levels of CPF has on blood esterase activities which are frequently used not only as biomarkers of exposure but also to set exposure levels in risk assessment. To determine this, male and female rat pups were exposed orally from postnatal day 10 to 16 to either corn oil (vehicle) or 0.5, 0.75, or 1.0 mg/kg CPF. At 12 h after the final exposure, serum cholinesterase (ChE), butyrylcholinesterase (BChE), and carboxylesterase (CES), and red blood cell (RBC) and brain AChE activities were determined. There were no differences between sexes in either the controls or individual treatments for all enzymes. Only the highest dosage of 1.0 mg/kg CPF yielded significant brain AChE inhibition (22-24%) but all dosages significantly inhibited the blood esterases with inhibition being highest with serum CES (65-85%) followed by serum BChE (57-76%), RBC AChE (35-65%), and then serum ChE (16-32%). Our data verify that blood esterases are inhibited at dosages of CPF that alter neurobehavioral performance in the absence of effects on brain AChE activity.

A narrative review of converging evidence addressing developmental toxicity of pyrethroid insecticides

Pyrethroid insecticides are broadly used in agriculture and household products throughout the world. Exposure to this class of insecticides is widespread, and while generally believed to be safe for use, there is increasing concern regarding their effects on neurodevelopment. Due to the critical roles that molecular targets of pyrethroids play in the regulation of neurodevelopment, particular focus has been placed on evaluating the effects of in utero and childhood pyrethroid exposure on child cognition and behavior. As such, this narrative review synthesizes an assessment of converging study types; we review reports of neonatal pyrethroid levels together with current epidemiological literature that convergently address the risk for developmental toxicity linked to exposure to pyrethroid insecticides. We first address studies that assess the degree of direct fetal exposure to pyrethroids in utero through measurements in cord blood, meconium, and amniotic fluid. We then focus on the links between prenatal exposure to these insecticides and child neurodevelopment, fetal growth, and other adverse birth outcomes. Furthermore, we assess the effects of postnatal exposure on child neurodevelopment through a review of the data on pediatric exposures and child cognitive and behavioral outcomes. Study quality was evaluated individually, and the weight of evidence was assessed broadly to characterize these effects. Overall, while definitive conclusions cannot be reached from the currently available literature, the available data suggest that the potential links between pyrethroid exposure and child neurodevelopmental effects deserve further investigation.

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.

Elements to increase translation in pyrethroid epidemiology research: A review

Pyrethroid insecticides have been the subject of numerous epidemiology studies in the past two decades. We examined the pyrethroids epidemiology literature published between 2016 and 2021. Our objective with this exercise was to inform interested readers regarding information on methodological elements that strengthen a study's use for translation (i.e., use in risk assessment) and to describe aspects of future research methods that could improve utility for decision-making. We focused on the following elements: (i) study design that provided evidence that pyrethroid exposure preceded the outcome, (ii) evidence that the method used for exposure characterization was reliable and sufficiently accurate for the intended purpose, and (iii) use of a robust approach for outcome ascertainment. For each of the 74 studies identified via the literature search, we categorized the methodological elements as Acceptable or Supplemental. A study with three Acceptable elements was considered Relevant for risk assessment purposes. Based on our evaluative approach, 18 (24%) of the 74 publications were considered to be Relevant. These publications were categorized as Acceptable for all three elements assessed: confirmed exposure (N = 24), confirmed outcome (N = 64), exposure preceded the outcome (N = 44). Three of these studies were birth cohorts. There were 15 Relevant publications of adults which included 10 Agricultural Health Study cohort publications of self-reported permethrin. Overall, the majority of the reviewed studies used methods that did not permit a determination that pyrethroid exposure preceded the outcome, and/or did not utilize robust methods for exposure assessment and outcome ascertainment. There is an opportunity for investigators and research sponsors to build on the studies reviewed here and to incorporate more translational approaches to studying exposure/outcome associations related to pesticides and other chemicals.

Household pesticide exposures and infant gross motor development in the MADRES cohort

BACKGROUND

The development of motor skills in infancy is a vital neurodevelopmental milestone. Although previous studies have explored the neurotoxic effects of agricultural pesticides on infants' motor development, limited research has examined early postnatal household pesticide use on infants' motor development, particularly among urban communities.

OBJECTIVE

This study examined the association between early postnatal household pesticide use and infants' gross and fine motor development at 6 months of age.

METHODS

Questionnaires were administered via telephone to 296 mother-infant dyads in the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) pregnancy cohort. Early life household pesticide use was assessed via questionnaire administered when infants turned 3 months old and gross and fine motor development was assessed by the Ages and Stages Questionnaire (ASQ-3) at 6 months old. Infant gross motor scores were reverse coded so that higher scores indicated lower gross motor performance. Negative binomial regressions were performed to assess the relationship between household pesticide use and infant gross motor development.

RESULTS

Infants were predominantly Hispanic (78.7%) and full term (gestational age at birth: 39.0 ± 1.9 weeks), with 22.3% of maternal participants reporting household use of rodent and insect pesticides. Adjusting for recruitment site, maternal age, ethnicity, household income, education, infant corrected age, infant sex, and home type, infants with maternal-reported household use of rodent and insect pesticides had 1.30 times higher expected gross motor scores (95% confiidence interval 1.05, 1.61) than infants with no reported use of household pesticides, with higher scores indicating reduced gross motor performance.

CONCLUSIONS

Our results suggest household use of rodent and insect pesticides may harm infants' gross motor development in early childhood. Future research should evaluate the impact of specific household chemicals in infant biospecimens and their associations with infant motor development to confirm these findings.

Systematic review of human biomonitoring studies of ethylenethiourea, a urinary biomarker for exposure to dithiocarbamate fungicides

Toxicological and epidemiological studies implicate exposure to dithiocarbamate (DTC) fungicides in adverse health outcomes. However, there is limited information about human exposure to these chemicals. This systematic review determined to which extent human populations worldwide, including children, pregnant women, and adults, are exposed environmentally or occupationally to DTC pesticides and how these exposures compare to the NHANES 2003-2008 population, using urinary ETU data as an outcome measure. PubMed, Embase, and SciFinder were searched using the keywords "ethylenethiourea" or CAS No.: 96-45-7, and urine or urinary. Duplicates and irrelevant studies were removed from the search results based on predetermined exclusion criteria. This screening process identified 17 relevant papers. One additional paper was found independent of this search. Data from studies were extracted using a pre-established data collection form. Ten, two, and five manuscripts reported urinary levels in environmentally exposed adults, children, and pregnant women, respectively. Median ETU levels ranged from 0.15 to 4.7 μg/g creatinine in adults (1994-2017), 0.24-0.83 μg/g creatinine in children (2011), and 2.6-5.24 ng/ml in pregnant women (2011). Eight studies reported urinary ETU levels in mostly agriculturally exposed populations, with median ETU levels ranging from 0.42 to 49.6 μg/g creatinine (1999-2011). With one exception, all studies were conducted between 1994 and 2011. ETU levels in the NHANES 2003-2008 population appeared to be generally lower than most studies identified in this review. This finding suggests that, historically, DTC fungicide exposures in the general population of high-income countries, such as the US, were low, whereas agricultural populations may have experienced higher exposure. Unfortunately, more recent exposure data are missing, especially in countries where DTC pesticides are not being phased out.

Role of endocrine disrupting chemicals in children's neurodevelopment

Environmental stressors, like endocrine disrupting chemicals (EDC), are considered important contributors to the increased rates of neurodevelopmental dysfunctions. Considering the cumulative research on adverse neurodevelopmental effects associated with prenatal exposure to EDC, the purpose of this study was to review the available limited literature about the effects of postnatal exposure to EDC on child neurodevelopment and behaviour. Despite widespread children's exposure to EDC, there are a limited number of epidemiological studies on the association of this exposure with neurodevelopmental disorders, in particular in the postnatal period. The available research suggests that postnatal EDC exposure is related to adverse neurobehavioral outcomes in children; however the underlying mechanisms of action remain unclear. Timing of exposure is a key factor determining potential neurodevelopmental consequences, hence studying the impact of multiple EDC co-exposure in different vulnerable life periods could guide the identification of sensitive subpopulations. Most of the reviewed studies did not take into account sex differences in the EDC effects on children neurodevelopment. We believe that the inclusion of sex in the study design should be considered as the role of EDC on children neurodevelopment are likely sex-specific and should be taken into consideration when determining susceptibility and potential mechanisms of action.

Recent pesticide exposure affects sleep: A cross-sectional study among smallholder farmers in Uganda

BACKGROUND

Poorly educated smallholder farmers in low-income countries are highly exposed to pesticides. This can result in adverse mental health issues, of which sleep problems might be an underlying indicator. We aim to examine the association between sleep problems and pesticide exposure among smallholder farmers in Uganda.

METHODS

A cross-sectional survey with 253 smallholder farmers was conducted between October and December 2019. Sleep problems were assessed during the week before the visit using the Medical Outcomes Study Sleep Scale (MOS-SS). Exposure to pesticides was assessed as application days of any pesticide and as use of 2,4-D, glyphosate, mancozeb, organophosphates & carbamates, pyrethroids and other pesticides during the week and year prior to the visit. Associations were assessed using adjusted multivariable logistic regression models.

RESULTS

Increased odds ratio (OR) for the sleep problem index 6-items (OR [95% Confidence Interval] 1.99 [1.04; 3.84] and 3.21 [1.33; 7.82]), sleep inadequacy (1.94 [1.04; 3.66] and 2.49 [1.05-6.22]) and snoring (3.17 [1.12; 9.41] and 4.07 [1.04; 15.14]) were observed for farmers who respectively applied pesticides up to two days and three or more days in the past week compared to farmers who did not apply during the past week. Gender-stratified analyses showed a higher OR for female applicators (4.27 [1.76-11.16]) than for male applicators (1.82 [0.91-3.79]) for the association between the sleep problem index 6-items and pesticide use in the week before the visit. Increased ORs were also observed for the association between the sleep problem index 6-item and mancozeb exposure during the past year 2.28 [1.12-4.71] and past week 2.51 [0.86-7.55] and glyphosate exposure during the past week 3.75 [1.24-11.8] compared to non-applicators.

DISCUSSION

Our findings suggest an increased risk of sleep problems among smallholder farmers in a pesticide-exposure-dependent way in a low-income context. Further gender-stratified, longitudinal investigations are warranted to confirm these findings.

Chlorpyrifos residue level and ADHD among children aged 1-6 years in rural China: A cross-sectional study

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders in childhood and is caused by both genetic and environmental factors. As genetic factors are nonmodifiable, environmental factors have attracted increasing attention.

OBJECTIVE

To investigate the relationships between urinary chlorpyrifos (CPF) levels, blood micronutrient levels, and ADHD prevalence in children living in rural areas of China.

METHODS

This cross-sectional study collected data on CPF exposure (according to urinary levels), blood micronutrient levels, and ADHD prevalence in children aged 1-6 years in rural China. The CPF levels were determined by mass spectrometry. Blood levels of micronutrients, including zinc, iron, calcium, copper, magnesium, and vitamin D, were measured by professional detection kits. ADHD was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. Descriptive statistics and univariate analysis were conducted using SPSS 21.0, and path analysis was conducted using Mplus 8.0.

RESULTS

Of the 738 children who met the eligibility criteria, 673 children (673/738, 91.2%) were included in the final analysis. Baseline questionnaires and urine samples were collected from all 673 subjects. A total of 672 children provided blood samples for micronutrient testing, and 651 completed the ADHD assessment. Approximately one-fifth of children (144/673, 21.4%) had detectable levels of CPF in their urine, and 6.9% (45/651) were diagnosed with ADHD. Path analysis showed that the total effect of CPF exposure on ADHD risk was 0.166 (P < 0.05), with a direct effect of 0.197 (P < 0.05) and an indirect effect of -0.031 (P < 0.05) via vitamin D. The mediating effect of urinary CPF levels on ADHD risk via vitamin D was 18.67%.

CONCLUSION

Higher levels of CPF exposure are associated with higher risk of ADHD. Additionally, increasing vitamin D levels may have a beneficial effect on the relationship between CPF exposure and ADHD risk. Our findings highlight the importance of modifying environmental factors to reduce ADHD risk and provide insight into future ADHD interventions.

[Playful Learning: a tool for Environmental Education]

INTRODUCTION

Playful learning for environmental education represents a participatory pedagogical mediation that considers the socio-environmental realities in which persons are immersed.

OBJECTIVE

To promote environmental education, through playful, participatory, and flexible methods, to prevent pesticide exposure.

METHODOLOGY

Using geographic information systems, the distances between schools and bananas plantations were calculated. A playful and constructivism methodology was designed for primary school students (6 - 8.5 years), and their legal guardians. Subsequently, 148 workshops were developed in 37 rural Costa Rican schools, in which 2757 children and 387 adults participated.

RESULTS

Thirty-eight percent (38 %) (n=14) of the schools were located at less than 100 meters from banana plantations. Playful communication generated a participatory environment, in which local needs were identified and collective knowledge was built about the effects of pesticide exposure on the environment and human health. Participants were able to identify the main preventive actions to reduce pesticide exposure.

CONCLUSIONS

Playful, participatory, and flexible methodologies in environmental education facilitate the process of sensitizing first cycle primary school students and their parents from rural communities about the risks of exposure to pesticides. The methodology used can be easily adapted for application in other environmental science studies.

Association Between Exposure to Pesticides and ADHD or Autism Spectrum Disorder: A Systematic Review of the Literature

OBJECTIVE

To conduct a systematic review of studies assessing the relationship between exposure to pesticides and ADHD or Autism Spectrum Disorder (ASD).

METHODS

Based on a pre-registered protocol in PROPSERO (CRD42018107847), we searched PubMed, Ovid databases, and ISI Web of Knowledge with no date/language/document type restrictions, up to May 2019. The Newcastle Ottawa Scale was used to assess study quality.

RESULTS

Among the 29 retained studies, 13 focused on ADHD, 14 on ASD, and two on both disorders. Ten studies reported a significant association between exposure to pesticides and ADHD/ADHD symptoms and 12 studies found a significant association with ASD/ASD traits. The strengths of the association and the possible confounders controlled for varied substantially across studies.

CONCLUSION

Whilst there is some evidence suggesting a possible link between pesticides and ADHD/ASD, heterogeneity across studies prevents firm conclusions. We provide methodological indications for future studies.

Exposome of attention deficit hyperactivity disorder in Taiwanese children: exploring risks of endocrine-disrupting chemicals

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) is diagnosed in ~7% of school-aged children. The role of endocrine-disrupting chemicals (EDC) and oxidative stress in ADHD etiology are not clear.

OBJECTIVE

Assessment of the associations between simultaneous exposure to multiple compounds and ADHD in children.

METHODS

The case-control study included 76 clinically diagnosed ADHD cases and 98 controls, aged 4-15 years old. Concentrations quartiles of urinary metabolites of acrylamide, acrolein, nonylphenol, phthalates, and organophosphate pesticides and biomarkers of oxidative stress were used to fit logistic regressions for each compound and weighted quantiles sum (WQS) regression for the mixture.

RESULTS

Positive dose-response relationships with ADHD were observed for 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA) (odds ratio(OR)_Q4 = 3.73, 95%CI [1.32, 11.04], p_trend = 0.003), dimethyl phosphate (DMP) (OR_Q4 = 4.04, 95%CI [1.34, 12.94], p_trend = 0.014) and diethyl phosphate (OR_Q4 = 2.61, 95%CI = [0.93, 7.66], p_trend = 0.030), and for the mixture of compounds (OR_WQS = 3.82, 95%CI = [1.78, 8.19]) with the main contributions from HNE-MA (28.9%) and DMP (18.4%).

CONCLUSIONS

The dose-response relationship suggests enhanced susceptibility to EDC burden in children even at lower levels, whereas the main risk is likely from organophosphate pesticides. HNE-MA is recommended as a sensitive biomarker of lipid peroxidation in the further elucidation of the oxidative stress role in ADHD etiology.

Psychometric Validation of a Questionnaire to Assess Perception and Knowledge About Exposure to Pesticides in Rural Schoolchildren of Maule, Chile

Exposure to pesticides during infancy is associated with numerous adverse health outcomes. The assessment of knowledge and perception of pesticides exposure and risk among children has not been thoroughly studied. The aim of the study was to evaluate the reliability and validity of a questionnaire that measures the knowledge and perception of exposure to organophosphate pesticides among rural schoolchildren. The questionnaire was administered to 151 schoolchildren between 9 and 13years from four Chilean rural schools. An internal consistency analysis of the ordinal alpha coefficient and a polychoric factor analysis for categorical data were used. The results show that the ordinal alpha was 0.95. Polychoric matrices of rotated components show the 17 questions summarized pesticide knowledge in five factors extracted after promax rotation. This factorial model explains 56.3% of the variance. The questions were grouped as follows: knowledge about pesticides (Factor 1); knowledge of health effects related to pesticides exposure (Factor 2); pesticide exposure through the growing of fruits and vegetables (Factor 3); perception and action against pesticides exposure at school (Factor 4); and perception and action against pesticides exposure at home (Factor 5). The questionnaire provides a useful tool for examining pesticide exposure in agricultural regions, allowing younger community members to participate.

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.