The neurotoxicity of organochlorine and pyrethroid pesticides

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

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

Exploring environmental exposomes and the gut-brain nexus: Unveiling the impact of pesticide exposure

This review delves into the escalating concern of environmental pollutants and their profound impact on human health in the context of the modern surge in global diseases. The utilisation of chemicals in food production, which results in residues in food, has emerged as a major concern nowadays. By exploring the intricate relationship between environmental pollutants and gut microbiota, the study reveals a dynamic bidirectional interplay, as modifying microbiota profile influences metabolic pathways and subsequent brain functions. This review will first provide an overview of potential exposomes and their effect to gut health. This paper is then emphasis the connection of gut brain function by analysing microbiome markers with neurotoxicity responses. We then take pesticide as example of exposome to elucidate their influence to biomarkers biosynthesis pathways and subsequent brain functions. The interconnection between neuroendocrine and neuromodulators elements and the gut-brain axis emerges as a pivotal factor in regulating mental health and brain development. Thus, manipulation of gut microbiota function at the onset of stress may offer a potential avenue for the prevention and treatment for mental disorder and other neurodegenerative illness.

Chemical effects on neural network activity: Comparison of acute versus network formation exposure in microelectrode array assays

New approach methodologies (NAMs) can address information gaps on potential neurotoxicity or developmental neurotoxicity hazard for data-poor chemicals. Two assays have been previously developed using microelectrode arrays (MEA), a technology which measures neural activity. The MEA acute network function assay (AcN) uses dissociated rat cortical cells cultured at postnatal day 0 and evaluates network activity during a 40-minute chemical exposure on day in vitro (DIV)13 or 15. In contrast, the MEA network formation assay (NFA) uses a developmental exposure paradigm spanning DIV0 through DIV12. Measures of network activity over time at DIV5, 7, 9, and 12 in the NFA are reduced to an estimated area under the curve to facilitate concentration-response evaluation. Here, we evaluated the hypothesis that chemicals with effects in the AcN also perturb the NFA by examining quantitative and qualitative concordance between assays. Out of 243 chemicals screened in both assays, we observed 70.3% concordance between the AcN and NFA after eliminating activity inferred to be cytotoxic (selective activity), with the majority of discordance explained by chemicals that altered selective activity in the AcN but not NFA. The NFA detected more active chemicals when evaluating activity associated with cytotoxicity. Median potency values were lower in the NFA compared to the AcN, but within-chemical potency values were not uniformly lower in the NFA than the AcN. Lastly, the AcN and NFA captured unique bioactivity fingerprints; the AcN was more informative for identifying chemicals with a shared mode of action, while the NFA provided information relevant to developmental exposure. Taken together, this analysis provides a rationale for using both approaches for chemical evaluation with consideration of the context of use, such as screening/ prioritization, hazard identification, or to address questions regarding biological mechanism or function.

Synergistic insights into pesticide persistence and microbial dynamics for bioremediation

Rampant use of fertilizers and pesticides for boosting agricultural crop productivity has proven detrimental impact on land, water, and air quality globally. Although fertilizers and pesticides ensure greater food security, their unscientific management negatively impacts soil fertility, structure of soil microbiome and ultimately human health and hygiene. Pesticides exert varying impacts on soil properties and microbial community functions, contingent on factors such as their chemical structure, mode of action, toxicity, and dose-response characteristics. The diversity of bacterial responses to different pesticides presents a valuable opportunity for pesticide remediation. In this context, OMICS technologies are currently under development, and notable advancements in gene editing, including CRISPR technologies, have facilitated bacterial engineering, opening promising avenues for reducing toxicity and enhancing biological remediation. This paper provides a holistic overview of pesticide dynamics, with a specific focus on organophosphate, organochlorine, and pyrethroids. It covers their occurrence, activity, and potential mitigation strategies, with an emphasis on the microbial degradation route. Subsequently, the pesticide degradation pathways, associated genes and regulatory mechanisms, associated OMICS approaches in soil microbes with a special emphasis on CRISPR/Cas9 are also being discussed. Here, we analyze key environmental factors that significantly impact pesticide degradation mechanisms and underscore the urgency of developing alternative strategies to diminish our reliance on synthetic chemicals.

Development of terpenoid repellents against Aedes albopictus: a combined study of biological activity evaluation and computational modelling

To explore novel terpenoid repellents, 22 candidate terpenoid derivatives were synthesized and tested for their electroantennogram (EAG) responses and repellent activities against Aedes albopictus. The results from the EAG experiments revealed that 5-(2-hydroxypropan-2-yl)-2-methylcyclohex-2-en-1-yl formate (compound 1) induced distinct EAG responses in female Aedes albopictus. At concentrations of 0.1, 1, 10, 100, and 1000 mg/L, the EAG response values for compound 1 were 179.59, 183.99, 190.38, 193.80, and 196.66 mV, demonstrating comparable or superior effectiveness to DEET. Repellent activity analysis indicated significant repellent activity for compound 1, closest to the positive control DEET. The in silico assessment of the ADMET profile of compound 1 indicates that it successfully passed the ADMET evaluation. Molecular docking studies exhibited favourable binding of compound 1 to the active site of the odorant binding protein (OBP) of Aedes albopictus, involving hydrophobic forces and hydrogen bond interactions with residues in the OBP pocket. The QSAR model highlighted the influential role of hydrogen-bonding receptors, positively charged surface area of weighted atoms, polarity parameters of molecules, and maximum nuclear-nuclear repulsion force of carbon-carbon bonds on the relative EAG response values of the tested compounds. This study holds substantial significance for the advancement of new terpenoid repellents.

Comparison between pollutants found in breast milk and infant formula in the last decade: A review

Since ancient times, breastfeeding has been the fundamental way of nurturing the newborn. The benefits of breast milk are widely known, as it is a source of essential nutrients and provides immunological protection, as well as developmental benefits, among others. However, when breastfeeding is not possible, infant formula is the most appropriate alternative. Its composition meets the nutritional requirements of the infant, and its quality is subject to strict control by the authorities. Nonetheless, the presence of different pollutants has been detected in both matrices. Thus, the aim of the present review is to make a comparison between the findings in both breast milk and infant formula in terms of contaminants in the last decade, in order to choose the most convenient option depending on the environmental conditions. For that, the emerging pollutants including metals, chemical compounds derived from heat treatment, pharmaceutical drugs, mycotoxins, pesticides, packaging materials, and other contaminants were described. While in breast milk the most concerning contaminants found were metals and pesticides, in infant formula pollutants such as metals, mycotoxins, and packaging materials were the most outstanding. In conclusion, the convenience of using a feeding diet based on breast milk or either infant formula depends on the maternal environmental circumstances. However, it is important to take into account the immunological benefits of the breast milk compared to the infant formula, and the possibility of using breast milk in combination with infant formula when the nutritional requirements are not fulfilled only with the intake of breast milk. Therefore, more attention should be paid in terms of analyzing these conditions in each case to be able to make a proper decision, as it will vary depending on the maternal and newborn environment.

Association between Organochlorine Pesticides and Vitamin D in Female Subjects

In human population studies, organochlorine pesticides (OCPs) have been linked to vitamin D deficiency. Therefore, this study examined the association between OCPs, vitamin D₃ (cholecalciferol, 25(OH)D₃), and the active metabolite 1,25-dihydrovitamin D₃ (1,25(OH)₂D₃) in a cohort of non-obese women. The serum samples of 58 female participants (age-31.9 ± 4.6 years; body mass index (BMI)-25.7 ± 3.7 kg/m²) were screened for 10 indicator OCPs. 25(OH)D₃ and 1,25(OH)₂D₃ levels were determined via isotope dilution liquid chromatography tandem mass spectrometry. In this cohort, the 25(OH)D₃ and 1,25(OH)₂D₃ levels were 22.9 ± 11.2 ng/mL and 0.05 ± 0.02 ng/mL, respectively, with 28 participants classified as 25(OH)D₃-deficient (<50 nmol/L). In the study cohort, no correlations were found between individual or total OCPs (ƩOCPs) and 25(OH)D₃. p,p'-dichlorodiphenyldichloroethylene (DDE) and ƩOCPs correlated positively with 1,25(OH)₂D₃, with the latter being negatively correlated with estimated glomerular filtration rate (eGFR). In women with sufficient 25(OH)D₃ levels, p,p'-dichlorodiphenyltrichloroethan (DDT) was positively correlated with 1,25(OH)₂D₃, whilst in the deficient group, hexachlorobenzene (HCB) and p,p'-(DDE) were positively correlated with 1,25(OH)₂D₃, β-Hexachlorocyclohexane (HCH) was positively correlated with 25(OH)D₃, and none of the OCPs were associated with measures of renal function. Overall, OCPs and ƩOCPs were not associated with 25(OH)D₃, suggesting that they are unrelated to vitamin D deficiency, but p,p'-DDE and ƩOCPs correlated positively with active 1,25(OH)₂D₃, while ƩOCPs correlated negatively with eGFR, suggesting a possible renal effect. Analysis of vitamin D deficiency revealed an association between β-HCH and 25(OH)D₃, and between HCB and p,p'-DDE and 1,25(OH)₂D₃, suggesting that OCP effects may be enhanced in cases of vitamin D deficiency.

Development of insecticide-impregnated polyester/cotton blend fabric and assessment of their repellent characteristics against Cimex lectularius and dengue vectors Aedes albopictus and Aedes aegypti

BACKGROUND

Personal protection measures using insecticide-treated fabric is one of the most effective strategies to prevent the bites of hematophagous insects. Many countries have had success treating fabrics with pyrethroids on an individual level.

METHODS

In the current study, a new combination of insecticides, alpha-cypermethrin (ACP) and deltamethrin (DET), has been impregnated on fabric composed of a 50:50 blend of polyester and cotton. Residual and morphological analysis was performed along with the evaluation of physical parameters. Biological evaluations were performed to check the repellency, knockdown, and mortality of insecticide-impregnated fabric (IIF) against bed bugs (Cimex lectularius) using Petri plate assay and mosquitoes (Aedes aegypti and Aedes albopictus) using cone bioassay.

RESULTS

The results showed the repellency of IIF to be 56.6% for C. lectularius and a knockdown percentage of 53.3% and 63.3% for Ae. aegypti and Ae. albopictus, respectively. A > 80% mortality was found for both species of mosquitoes up to 20 cycles of washing with no significant difference (P > 0.05). From high-performance liquid chromatography (HPLC) analysis, the reduction in the contents of ACP and DET after subsequent washes can be correlated with the overall decrease in bioefficacy. ACP and DET remaining in unit gram of fabric after 20 wash cycles were found to be 5.4 mg and 3.1 mg, respectively. By examining the fabric's surface morphology using scanning electron microscope (SEM) and utilizing energy-dispersive x-ray (EDX) analysis, it was possible to identify the presence of insecticides that were adhered to the fabric. Differential scanning calorimetry (DSC) showed distinctive endothermic peak of insecticide at 98.3 ºC, whereas no change in thermal behavior was observed from thermo-gravimetric analysis (TGA). Furthermore, the physical attributes of IIF provide conclusive evidence for its firmness.

CONCLUSION

All experimental findings were consistent with the potential use of IIF as a bed bug- and mosquito-repellent fabric to be used against hematophagous infestations. This fabric can serve as a potential strategy to control vector-borne diseases like dengue, malaria, trench fever, etc.

Effects of pyrethroids on the cerebellum and related mechanisms: a narrative review

Pyrethroids (PYRs) are a group of synthetic organic chemicals that mimic natural pyrethrins. Due to their low toxicity and persistence in mammals, they are widely used today. PYRs exhibit higher lipophilicity than other insecticides, which allows them to easily penetrate the blood-brain barrier and directly induce toxic effects on the central nervous system. Several studies have shown that the cerebellum appears to be one of the regions with the largest changes in biomarkers. The cerebellum, which is extremely responsive to PYRs, functions as a crucial region for storing motor learning memories. Exposure to low doses of various types of PYRs during rat development resulted in diverse long-term effects on motor activity and coordination functions. Reduced motor activity may result from developmental exposure to PYRs in rats, as indicated by delayed cerebellar morphogenesis and maturation. PYRs also caused adverse histopathological and biochemical changes in the cerebellum of mothers and their offspring. By some studies, PYRs may affect granule cells and Purkinje cells, causing damage to cerebellar structures. Destruction of cerebellar structures and morphological defects in Purkinje cells are known to be directly related to functional impairment of motor coordination. Although numerous data support that PYRs cause damage to cerebellar structures, function and development, the mechanisms are not completely understood and require further in-depth studies. This paper reviews the available evidence on the relationship between the use of PYRs and cerebellar damage and discusses the mechanisms of PYRs.

Pesticides and tremor: An overview of association, mechanisms and confounders

Pesticides are a heterogeneous class of chemicals mainly used for the protection of crops from pests. Because of their very widespread use, acute or/and chronic exposure to these chemicals can lead to a plethora of sequelae inflicting diseases, many of which involve the nervous system. Tremor has been associated with pesticide exposure in human and animal studies. This review is aimed at assessing the studies currently available on the association between the various types of pesticides/insecticides and tremor, while also accounting for potential confounding factors. To our knowledge, this is the first coherent review on the subject. After appraising the available evidence, we call for more intensive research on this topic, as well as intonate the need of implementing future preventive measures to protect the exposed populations and to reduce potential disabilities and social drawbacks.

Pesticides and the Microbiome-Gut-Brain Axis: Convergent Pathways in the Pathogenesis of Parkinson's Disease

The increasing global burden of Parkinson's disease (PD), termed the PD pandemic, is exceeding expectations related purely to population aging and is likely driven in part by lifestyle changes and environmental factors. Pesticides are well recognized risk factors for PD, supported by both epidemiological and experimental evidence, with multiple detrimental effects beyond dopaminergic neuron damage alone. The microbiome-gut-brain axis has gained much attention in recent years and is considered to be a significant contributor and driver of PD pathogenesis. In this narrative review, we first focus on how both pesticides and the microbiome may influence PD initiation and progression independently, describing pesticide-related central and peripheral neurotoxicity and microbiome-related local and systemic effects due to dysbiosis and microbial metabolites. We then depict the bidirectional interplay between pesticides and the microbiome in the context of PD, synthesizing current knowledge about pesticide-induced dysbiosis, microbiome-mediated alterations in pesticide availability, metabolism and toxicity, and complex systemic pesticide-microbiome-host interactions related to inflammatory and metabolic pathways, insulin resistance and other mechanisms. An overview of the unknowns follows, and the role of pesticide-microbiome interactions in the proposed body-/brain-first phenotypes of PD, the complexity of environmental exposures and gene-environment interactions is discussed. The final part deals with possible further steps for translation, consisting of recommendations on future pesticide use and research as well as an outline of promising preventive/therapeutic approaches targeted on strengthening or restoring a healthy gut microbiome, closing with a summary of current gaps and future perspectives in the field.

Characterization in Potent Modulation on Voltage-Gated Na+ Current Exerted by Deltamethrin, a Pyrethroid Insecticide

Deltamethrin (DLT) is a type-II pyrethroid ester insecticide used in agricultural and domestic applications as well as in public health. However, transmembrane ionic channels perturbed by this compound remain largely unclear, although the agent is thought to alter the gating characteristics of voltage-gated Na⁺ (Na_V) channel current. In this study, we reappraised whether and how it and other related compounds can make any further modifications on voltage-gated Na⁺ current (I_Na) in pituitary tumor (GH₃) cells. Cell exposure to DLT produced a differential and dose-dependent stimulation of peak (transient, I_Na(T)) or sustained (late, I_Na(L)) I_Na; consequently, the EC₅₀ value required for DLT-stimulated I_Na(T) or I_Na(L) was determined to be 11.2 or 2.5 μM, respectively. However, neither the fast nor slow component in the inactivation time constant of I_Na(T) activated by short depolarizing pulse was changed with the DLT presence; conversely, tefluthrin (Tef), a type-I pyrethroid insecticide, can accentuate I_Na with a slowing in inactivation time course of the current. The I_Na(L) augmented by DLT was attenuated by further application of either dapagliflozin (Dapa) or amiloride, but not by chlorotoxin. During pulse train (PT) stimulation, with the Tef or DLT presence, the cumulative inhibition of I_Na(T) became slowed; moreover, following PT stimuli, a large tail current with a slowly recovering process was observed. Alternatively, during rapid depolarizing pulse, the amplitude of I_Na(L) and tail I_Na (I_Na(Tail)) for each depolarizing pulse became progressively increased by adding DLT, not by Tef. The recovery time constant following PT stimulation with continued presence of Tef or DLT was shortened by further addition of Dapa. The voltage-dependent hysteresis (Hys_(V)) of persistent I_Na was differentially augmented by Tef or DLT. Taken together, the magnitude, gating, frequency dependence, as well as Hys_(V) behavior of I_Na exerted by the presence of DLT or Tef might exert a synergistic impact on varying functional activities of excitable cells in culture or in vivo.

Evaluation of Toxic Effects Induced by Sub-Acute Exposure to Low Doses of α-Cypermethrin in Adult Male Rats

To contribute new information to the pyrethroid pesticide α-cypermethrin toxicity profile, we evaluated its effects after oral administration to Wistar rats at daily doses of 2.186, 0.015, 0.157, and 0.786 mg/kg bw for 28 days. Evaluations were performed using markers of oxidative stress, cholinesterase (ChE) activities, and levels of primary DNA damage in plasma/whole blood and liver, kidney, and brain tissue. Consecutive exposure to α-cypermethrin affected the kidney, liver, and brain weight of rats. A significant increase in concentration of the thiobarbituric acid reactive species was observed in the brain, accompanied by a significant increase in glutathione peroxidase (GPx) activity. An increase in GPx activity was also observed in the liver of all α-cypermethrin-treated groups, while GPx activity in the blood was significantly lower than in controls. A decrease in ChE activities was observed in the kidney and liver. Treatment with α-cypermethrin induced DNA damage in the studied cell types at almost all of the applied doses, indicating the highest susceptibility in the brain. The present study showed that, even at very low doses, exposure to α-cypermethrin exerts genotoxic effects and sets in motion the antioxidative mechanisms of cell defense, indicating the potential hazards posed by this insecticide.

Impact of Environmental Risk Factors on Mitochondrial Dysfunction, Neuroinflammation, Protein Misfolding, and Oxidative Stress in the Etiopathogenesis of Parkinson's Disease

As a prevalent progressive neurodegenerative disorder, Parkinson's disease (PD) is characterized by the neuropathological hallmark of the loss of nigrostriatal dopaminergic (DAergic) innervation and the appearance of Lewy bodies with aggregated α-synuclein. Although several familial forms of PD have been reported to be associated with several gene variants, most cases in nature are sporadic, triggered by a complex interplay of genetic and environmental risk factors. Numerous epidemiological studies during the past two decades have shown positive associations between PD and several environmental factors, including exposure to neurotoxic pesticides/herbicides and heavy metals as well as traumatic brain injury. Other environmental factors that have been implicated as potential risk factors for PD include industrial chemicals, wood pulp mills, farming, well-water consumption, and rural residence. In this review, we summarize the environmental toxicology of PD with the focus on the elaboration of chemical toxicity and the underlying pathogenic mechanisms associated with exposure to several neurotoxic chemicals, specifically 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), rotenone, paraquat (PQ), dichloro-diphenyl-trichloroethane (DDT), dieldrin, manganese (Mn), and vanadium (V). Our overview of the current findings from cellular, animal, and human studies of PD provides information for possible intervention strategies aimed at halting the initiation and exacerbation of environmentally linked PD.

Advances and future prospects of pyrethroids: Toxicity and microbial degradation

Pyrethroids are a class of insecticides structurally similar to that of natural pyrethrins. The application of pyrethrins in agriculture and pest control lead to many kinds of environmental pollution affecting human health and loss of soil microbial population that affect soil fertility and health. Natural pyrethrins have been used since ancient times as insect repellers, and their synthetic versions especially type 2 pyrethroids could be highly toxic to humans. PBO (Piperonyl butoxide) is known to enhance the toxicity of prallethrin in humans due to the resistance in its metabolic degradation. Pyrethroids are also known to cause plasma biochemical profile changes in humans and they also lead to the production of high levels of reactive oxygen species. Further they are also known to increase SGPT activity in humans. Due to the toxicity of pyrethrins in water bodies, soils, and food products, there is an urgent need to develop sustainable approaches to reduce their levels in the respective fields, which are eco-friendly, economically viable, and socially acceptable for on-site remediation. Keeping this in view, an attempt has been made to analyse the advances and prospects in using pyrethrins and possible technologies to control their harmful effects. The pyrethroid types, composition and biochemistry of necessary pyrethroid insecticides have been discussed in detail, in the research paper, along with their effect on insects and humans. It also covers the impact of pyrethroids on different plants and soil microbial flora. The second part deals with the microbial degradation of the pyrethroids through different modes, i.e., bioaugmentation and biostimulation. Many microbes such as Acremonium, Aspergillus, Microsphaeropsis, Westerdykella, Pseudomonas, Staphylococcus have been used in the individual form for the degradation of pyrethroids, while some of them such as Bacillus are even used in the form of consortia.

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

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

Role of Environmental Toxicants on Neurodegenerative Disorders

Neurodegeneration leads to the loss of structural and functioning components of neurons over time. Various studies have related neurodegeneration to a number of degenerative disorders. Neurological repercussions of neurodegeneration can have severe impacts on the physical and mental health of patients. In the recent past, various neurodegenerative ailments such as Alzheimer’s and Parkinson’s illnesses have received global consideration owing to their global occurrence. Environmental attributes have been regarded as the main contributors to neural dysfunction-related disorders. The majority of neurological diseases are mainly related to prenatal and postnatal exposure to industrially produced environmental toxins. Some neurotoxic metals, like lead (Pb), aluminium (Al), Mercury (Hg), manganese (Mn), cadmium (Cd), and arsenic (As), and also pesticides and metal-based nanoparticles, have been implicated in Parkinson’s and Alzheimer’s disease. The contaminants are known for their ability to produce senile or amyloid plaques and neurofibrillary tangles (NFTs), which are the key features of these neurological dysfunctions. Besides, solvent exposure is also a significant contributor to neurological diseases. This study recapitulates the role of environmental neurotoxins on neurodegeneration with special emphasis on major neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease.

What can we learn from commercial insecticides? Efficacy, toxicity, environmental impacts, and future developments

Worldwide pesticide usage was estimated in up to 3.5 million tons in 2020. The number of approved products varies among different countries, however, in Brazil, there are nearly 5000 of such products available. Among them, insecticides correspond to a group of mounting importance for controlling crop pests and disease-associated vectors in public health. Unfortunately, resistance to commercially approved insecticides is commonly observed, limiting the use of these products. Thus, the search for more effective and environmentally friendly products is both a challenge and a necessity since several insecticides are no longer allowed in many countries. In this review, we discuss the historical strategies used in the development of modern insecticides, including chemical structure alterations, mechanism of action and their impact on insecticidal activity. The environmental impact of each pesticide class is also discussed, with persistence data and activity on non-target organisms, along with the human toxicological effect. By tracing the historical route of discovery and development of blockbuster pesticides like DDT, pyrethroids and organophosphates, we also aim to categorize and relate the successful chemical alterations and novel pesticide development strategies that resulted in safer alternatives. A brief discussion on the Brazilian registration procedure and a perspective of insecticides currently approved in the country was also included.

Occupational exposures to pesticides and other chemicals: a New Zealand motor neuron disease case–control study

Objectives

To assess associations between occupational exposures to pesticides and other chemicals and motor neuron disease (MND).

Methods

A population-based case–control study that included 319 MND cases (64% male/36% female) recruited through the New Zealand MND Association complemented with hospital discharge data, and 604 controls identified from the Electoral Roll. For each job held, a questionnaire collected information on 11 exposure categories (dust, fibres, tobacco smoke, fumes, gas, fumigants, oils/solvents, acids/alkalis, pesticides, other chemicals and animals/animal products). ORs were estimated using logistic regression adjusting for age, sex, ethnicity, socioeconomic status, education, smoking, alcohol consumption, physical activities, head/spine injury and other occupational exposures.

Results

Two exposure categories were associated with increased MND risks: pesticides (OR 1.70, 95% CI 1.17 to 2.48) and fumigants (OR 3.98, 95% CI 1.81 to 8.76), with risks increasing with longer exposure duration (p<0.01). Associations were also observed for: methyl bromide (OR 5.28, 95% CI 1.63 to 17.15), organochlorine insecticides (OR 3.28, 95% CI 1.18 to 9.07), organophosphate insecticides (OR 3.11, 95% CI 1.40 to 6.94), pyrethroid insecticides (OR 6.38, 95% CI 1.13 to 35.96), inorganic (copper) fungicides (OR 4.66, 95% CI 1.53 to 14.19), petrol/diesel fuel (OR 2.24, 95% CI 1.27 to 3.93) and unspecified solvents (OR 1.91, 95% CI 1.22 to 2.99). In women, exposure to textile fibres (OR 2.49, 95% CI 1.13 to 5.50), disinfectants (OR 9.66, 95% CI 1.29 to 72.44) and cleaning products (OR 3.53, 95% CI 1.64 to 7.59) were also associated with MND; this was not observed in men (OR 0.80, 95% CI 0.44 to 1.48; OR 0.72, 95% CI 0.29 to 1.84; OR 0.57, 95% CI 0.21 to 1.56, respectively).

Conclusions

This study adds to the evidence that pesticides, especially insecticides, fungicides, and fumigants, are risk factors for MND.

Analysis method development and health risk assessment of pesticide and heavy metal residues in Dendrobium Candidum

Herbal medicines that are widely used worldwide are easily contaminated by pesticides and heavy metals, threatening human health. In this study, a modified QuEChERS pre-treatment method combined with HPLC/GC-MS/MS was established for the determination of 24 pesticide residues in Dendrobium candidum. The average recoveries of 24 pesticides in D. candidum were 76.9-110.0% with the relative standard deviation (RSD) of 0.28-11.40%, and their limits of detection (LOD) and limits of quantitation (LOQ) were 0.005-10 and 0.011-22 μg kg^-1, respectively. The results showed that 83.33% of all samples had detected pesticide residues with the concentrations of 0.06-312.83 μg kg^-1. Meanwhile, microwave digestion combined with ICP-MS was used to detect the residues of 8 heavy metals in D. candidum. The average recoveries of 8 heavy metals were 82.7-108.1% with an RSD of 1.4-8.0%, and their LOD and LOQ were 0.0001-0.05 mg kg^-1 and 0.0003-0.2 mg kg^-1, respectively. The results indicated that 8 heavy metals were all detected in all samples, and the highest concentration of Zn was 11.97 mg kg^-1. Furthermore, the health risk assessment showed that the risk of the detected pesticides and heavy metals in samples to humans, specifically to the general population including adults and children, was acceptable.

Basic characteristics of EEG epileptiform discharges triggered by lindane in a model of experimental prostatitis

Introduction: Chronic prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS) is the most commonly diagnosed non-infectious prostatitis in urology. Studies have shown that CP/CPPS can induce neuroinflammation, which may result in CNS hyperexcitability and a tendency to develop epileptic seizures. Spike salvos are ictal EEG graph elements typical for the experimental model of lindane-induced seizures. There are a number of mathematical models for quantitative analysis of EEG, including the Fast Fourier Transform (FFT). It transforms the signal from time into the frequency domain, providing information on Power Spectral Densities (PSD). Aim: The aim of this study was to investigate the basic characteristics of epileptiform discharges induced by subconvulsive dose of lindane in rats, with experimentally induced CP/CPPS. Material and methods: CP/CPPS was induced by intraprostatic injection of 3% l-carrageenan in male Wistar albino rats. Animals with CP/CPPS were implanted with EEG registration electrodes, and then administered lindane (4 mg/kg, i.p, experimental group, n = 6 per group) or its solvent (DMSO, control group, n = 6 per group). An 8-channel EEG device was used in combination with software developed in the laboratory (NeuroSciLaBG). Ictal EEG epochs were extracted from the original signal and FFT analysis was performed to obtain information taking into account PSD in predefined frequency bands. Results: There was no ictal activity in the EEG of control animals. In experimental animals, ictal activity occurred and the mean duration of the ictal period was 2.06 s. FFT analysis revealed that the Alpha frequency range (7-15 Hz) was markedly dominant during ictal activity. Conclusion: The results of this study showed the characteristics of epileptiform discharges in animals with experimentally induced CP/CPPS. This study and animal model are suitable for future translational studies of the comorbidities of this syndrome.

Exposure to Sub-Lethal Doses of Permethrin Is Associated with Neurotoxicity: Changes in Bioenergetics, Redox Markers, Neuroinflammation and Morphology

Permethrin (PERM) is a member of the class I family of synthetic pyrethroids. Human use has shown that it affects different systems, with wide health dysfunctions. Our aim was to determine bioenergetics, neuroinflammation and morphology changes, as redox markers after subacute exposure to PERM in rats. We used MDA determination, protein carbonyl assay, mitochondrial O₂ consumption, expression of pro-inflammatory cytokines and a deep histopathological analysis of the hippocampus. PERM (150 mg/kg and 300 mg/kg body weight/day, o.v.) increased lipoperoxidation and carbonylated proteins in a dose-dependent manner in the brain regions. The activities of antioxidant enzymes glutathione peroxidase, reductase, S-transferase, catalase, and superoxide dismutase showed an increase in all the different brain areas, with dose-dependent effects in the cerebellum. Cytokine profiles (IL-1β, IL-6 and TNF-α) increased in a dose-dependent manner in different brain tissues. Exposure to 150 mg/kg of permethrin induced degenerated and/or dead neurons in the rat hippocampus and induced mitochondrial uncoupling and reduction of oxidative phosphorylation and significantly decreased the respiratory parameters state 3-associated respiration in complex I and II. PERM exposure at low doses induces reactive oxygen species production and imbalance in the enzymatic antioxidant system, increases gene expression of pro-inflammatory interleukins, and could lead to cell damage mediated by mitochondrial functional impairment.

Neurodevelopmental impact of the offspring by thyroid hormone system-disrupting environmental chemicals during pregnancy

Everyday use chemicals have been demonstrated to be endocrine disruptors. Since normal thyroid function during pregnancy is transcendental for the neurodevelopment of the offspring, knowledge of endocrine disrupting chemicals (EDC) is of main importance. The aim of our study is to recognize and describe EDC actions in pregnant women and focus on neurodevelopmental processes that can lead to neurotransmitter imbalance and cognitive impairment, and the possible clinical outcomes in the newborn and child. We searched PubMed databases for animal studies and clinical trials evaluating chemicals recognized as thyroid disruptors -perchlorate, phthalates, bisphenol A-, as well as chemicals with potential thyroid disruption activity -parabens, pesticides and persistent organic pollutants, on thyroid hormones (THs) levels and their bioavailability during pregnancy, and the outcome in newborns, infants and children. We also exhibit evidence from worldwide cohort studies to this regard. The publications reviewed show: 1) known endocrine disruptors have an association with hormonal thyroid levels, where an effect of increase or decrease in TH concentrations has been reported depending on the chemical exposed 2) associations between TH, EDCs and neurocognitive disorders have been addressed, such as ADHD, though no conclusive impact on potential related disorders as autism has been established, 3) perchlorate has demonstrated effects on thyroid levels on iodine uptake. In conclusion, detrimental risks and long-term consequences after in-utero exposure to EDCs are being reported in several cohort studies and further research must be conducted to establish a well-known cause-effect association.

[Procyanidin B2 protects neurons from cypermethrin-induced oxidative stress through the P13K/Akt/Nrf2 signaling pathway]

OBJECTIVE

To explore whether procyanidin B2 (PCB2) regulates the P13K/Akt/Nrf2 signaling pathway to protect neurons from oxidative stress induced by cypermethrin (CYP).

METHODS

Primary cultures of cerebral cortex neurons from C57BL/6 mice were randomly divided into 5 groups: normal control group (cultured in serum-free neurobasal-B27 medium), PCB2 treatment group(treated with 5 μg/mL PCB2 for 24 h), CYP exposure group(treated with 50 μmol/L CYP for 24 h), PCB2 pretreatment group(pretreated with 5 μg/mL PCB2 for 30 min followed by exposure to 50 μmol/L CYP for 24 h), and LY294002 treatment group (pretreated with 20 μmol/L LY294002 for 30 min before treatment with PCB2 for 30 min and then CYP for 24 h).CCK-8 assay was used to analyze the neuronal viability after the treatments.Reactive oxygen species (ROS) production in the cells was detected using the fluorescent probe DCFH-DA and flow cytometry.The changes in nuclear morphology and mitochondrial membrane potential of the cells were examined with Hoechst 33342 and JC-1 staining, respectively.Western blotting was performed to detect the protein expressions of Nrf2, HO-1, p-Akt and Akt in the cells.

RESULTS

In CYP exposure group, the cells showed significantly decreased viability and mitochondrial membrane potential with obvious apoptotic morphological changes and abnormal ROS production.By comparison, the cells in PCB2 preconditioning group showed improved cell survival rate, reduced abnormalities in nuclear morphology, increased mitochondrial membrane potential, and lowered intracellular ROS production.CYP exposure caused Nrf2 nuclear translocation and up-regulated Nrf2, HO-1, p-Akt protein expressions in the cells, which were inhibited by PCB2 pretreatment.Inhibition of the P13K/Akt signaling pathway obviously neutralized the protective effect of PCB2 against CYP-induced neuronal injury.

CONCLUSIONS

PCB2 regulates the Nrf2/ARE signaling pathway by activating the P13K/Akt signaling pathway to protect mouse cerebral cortical neurons against oxidative injury induced by cypermethrin.

Comparison of Acute Effects of Neurotoxic Compounds on Network Activity in Human and Rodent Neural Cultures

Assessment of neuroactive effects of chemicals in cell-based assays remains challenging as complex functional tissue is required for biologically relevant readouts. Recent in vitro models using rodent primary neural cultures grown on multielectrode arrays allow quantitative measurements of neural network activity suitable for neurotoxicity screening. However, robust systems for testing effects on network function in human neural models are still lacking. The increasing number of differentiation protocols for generating neurons from human-induced pluripotent stem cells (hiPSCs) holds great potential to overcome the unavailability of human primary tissue and expedite cell-based assays. Yet, the variability in neuronal activity, prolonged ontogeny and rather immature stage of most neuronal cells derived by standard differentiation techniques greatly limit their utility for screening neurotoxic effects on human neural networks. Here, we used excitatory and inhibitory neurons, separately generated by direct reprogramming from hiPSCs, together with primary human astrocytes to establish highly functional cultures with defined cell ratios. Such neuron/glia cocultures exhibited pronounced neuronal activity and robust formation of synchronized network activity on multielectrode arrays, albeit with noticeable delay compared with primary rat cortical cultures. We further investigated acute changes of network activity in human neuron/glia cocultures and rat primary cortical cultures in response to compounds with known adverse neuroactive effects, including gamma amino butyric acid receptor antagonists and multiple pesticides. Importantly, we observed largely corresponding concentration-dependent effects on multiple neural network activity metrics using both neural culture types. These results demonstrate the utility of directly converted neuronal cells from hiPSCs for functional neurotoxicity screening of environmental chemicals.

Endocrine disruptors also function as nervous disruptors and can be renamed endocrine and nervous disruptors (ENDs)

Endocrine disruption (ED) and endocrine disruptors (EDs) emerged as scientific concepts in 1995, after numerous chemical pollutants were found to be responsible for reproductive dysfunction. The World Health Organization established in the United Nations Environment Programme a list of materials, plasticizers, pesticides, and various pollutants synthesized from petrochemistry that impact not only reproduction, but also hormonal functions, directly or indirectly. Cells communicate via either chemical or electrical signals transmitted within the endocrine or nervous systems. To investigate whether hormone disruptors may also interfere directly or indirectly with the development or functioning of the nervous system through either a neuroendocrine or a more general mechanism, we examined the scientific literature to ascertain the effects of EDs on the nervous system, specifically in the categories of neurotoxicity, cognition, and behaviour. To date, we demonstrated that all of the 177 EDs identified internationally by WHO are known to have an impact on the nervous system. Furthermore, the precise mechanisms underlying this neurodisruption have also been established. It was previously believed that EDs primarily function via the thyroid. However, this study presents substantial evidence that approximately 80 % of EDs operate via other mechanisms. It thus outlines a novel concept: EDs are also neurodisruptors (NDs) and can be collectively termed endocrine and nervous disruptors (ENDs). Most of ENDs are derived from petroleum residues, and their various mechanisms of action are similar to those of "spam" in electronic communications technologies. Therefore, ENDs can be considered as an instance of spam in a biological context.

An Overview on the Potential Hazards of Pyrethroid Insecticides in Fish, with Special Emphasis on Cypermethrin Toxicity

Simple Summary

Pyrethroid insecticides are extensively used in controlling agricultural insects and treatment of ectoparasitic infestation in farm animals. However, the unhygienic disposable and seepage of pyrethroids from the agricultural runoff will lead to contamination of the aquatic ecosystems, which will, in turn, induce harmful toxic effects in the exposed living aquatic organisms, including fish. Cypermethrin (CYP) is a commonly and widely used type II pyrethroid insecticide with known dangerous toxic effects on the exposed organisms. Serious hazardous effects of these toxicants have been reported in several fish species leading to high mortalities and economic losses of the exposed fish.

Abstract

Pesticides are chemicals used to control pests, such as aquatic weeds, insects, aquatic snails, and plant diseases. They are extensively used in forestry, agriculture, veterinary practices, and of great public health importance. Pesticides can be categorized according to their use into three major types (namely insecticides, herbicides, and fungicides). Water contamination by pesticides is known to induce harmful impacts on the production, reproduction, and survivability of living aquatic organisms, such as algae, aquatic plants, and fish (shellfish and finfish species). The literature and information present in this review article facilitate evaluating the toxic effects from exposure to various fish species to different concentrations of pesticides. Moreover, a brief overview of sources, classification, mechanisms of action, and toxicity signs of pyrethroid insecticides in several fish species will be illustrated with special emphasis on Cypermethrin toxicity.

Recent Advances on Detection of Insecticides Using Optical Sensors

Insecticides are enormously important to industry requirements and market demands in agriculture. Despite their usefulness, these insecticides can pose a dangerous risk to the safety of food, environment and all living things through various mechanisms of action. Concern about the environmental impact of repeated use of insecticides has prompted many researchers to develop rapid, economical, uncomplicated and user-friendly analytical method for the detection of insecticides. In this regards, optical sensors are considered as favorable methods for insecticides analysis because of their special features including rapid detection time, low cost, easy to use and high selectivity and sensitivity. In this review, current progresses of incorporation between recognition elements and optical sensors for insecticide detection are discussed and evaluated well, by categorizing it based on insecticide chemical classes, including the range of detection and limit of detection. Additionally, this review aims to provide powerful insights to researchers for the future development of optical sensors in the detection of insecticides.

Pyrethroid based pesticides - chemical and biological aspects

Human and animal welfare primarily depends on the availability of food and surrounding environment. Over a century and half, the quest to identify agents that can enhance food production and protection from vector borne diseases resulted in the identification and use of a variety of pesticides, of which the pyrethroid based ones emerged as the best choice. Pesticides while improved the quality of life, on the other hand caused enormous health risks. Because of their percolation into drinking water and food chain and usage in domestic settings, humans unintentionally get exposed to the pesticides on a daily basis. The health hazards of almost all known pesticides at a variety of doses and exposure times are reported. This review provides a comprehensive summation on the historical, epidemiological, chemical and biological (physiological, biochemical and molecular) aspects of pyrethroid based insecticides. An overview of the available knowledge suggests that the synthetic pyrethroids vary in their chemical and toxic nature and pose health hazards that range from simple nausea to cancers. Despite large number of reports, studies that focused on identifying the health hazards using doses that are equivalent or relevant to human exposure are lacking. It is high time such studies are conducted to provide concrete evidence on the hazards of consuming pesticide contaminated food. Policy decisions to decrease the residual levels of pesticides in agricultural products and also to encourage organic farming is suggested.

Acute toxicity of organophosphate pesticide profenofos, pyrethroid pesticide λ cyhalothrin and biopesticide azadirachtin and their sublethal effects on growth and oxidative stress enzymes in benthic oligochaete worm, Tubifex tubifex

The present study was aimed to assess the acute toxicity of organophosphate pesticide, profenofos; synthetic pyrethroid pesticide, λ cyhalothrin and biopesticide, azadirachtin and their sublethal effects on growth rate and oxidative stress biomarkers in Tubifex tubifex in vivo. The results showed that 96 h LC₅₀ value of profenofos, λ cyhalothrin and azadirachtin to Tubifex tubifex are 0.59, 0.13 and 82.15 mg L^-1 respectively. Pesticide treated worms showed several behavioral abnormalities including increased mucus secretion, erratic movements, wrinkling activity and decreased clumping tendency during acute exposure. The percentage of autotomy increased significantly (p < 0.05) with the increasing concentration of the pesticides at 96 h of exposure. Sublethal concentrations of profenofos (0.059 and 0.118 mg L^-1), λ cyhalothrin (0.013 and 0.026 mg L^-1) and azadirachtin (8.2 and 16.4 mg L^-1) caused significant alterations in growth rate and oxidative stress enzymes in T. tubifex during 14 days exposure period. The growth rate of the pesticide exposed worms decreased significantly (P < 0.05) in a concentration and duration-dependent manner. Superoxide dismutase (SOD), reduced glutathione (GSH), glutathione-s-transferase (GST) and glutathione peroxidase (GPx) demonstrated a noteworthy (p < 0.05) initial induction followed by a subsequent reduction, while catalase (CAT) and malondialdehyde (MDA) exhibited noteworthy induction (p < 0.05) all through the exposure time. Through principal component analysis, correlation matrix, and integrated biomarker response, the effects of profenofos, λ cyhalothrin and azadirachtin on T. tubifex were distinguished. These results indicate that exposure to profenofos, λ cyhalothrin and azadirachtin affect survivability, change the behavioral responses, reduce the growth rate and induce oxidative stress enzymes in T. tubifex.

Microextraction by packed sorbent of selected pesticides in coffee samples employing ionic liquids supported on graphene nanosheets as extraction phase

This paper describes the synthesis, characterization, and use of ionic liquids supported on silica, functionalized with graphene oxide through covalent bonding (ILz/Si@GO), as sorbents for microextraction by packed sorbent (MEPS). Seven selected pesticides (diazinon, heptachlor, aldrin, endrin, dieldrin, endosulfan, and methoxychlor), used for the prevention of pests in coffee crops, and endosulfan sulfate-an endosulfan metabolite-were selected for this study as model compounds for evaluating the sorbent performance of the synthesized materials in the MEPS device. The cycles of each of the stages were previously optimized through univariate experiments to carry out the extraction. The ILz/Si@GO phase was compared to other sorbents used in MEPS (GO, DVB-MMA, C₄/SiO₂, C₈/SiO₂, ILz/SiO₂, and bare silica) and also with graphene functionalized through other methodologies, where ILz/Si@GO showed the best results. The material was characterized using a range of techniques. The selectivity of the sorbent material and its adsorption capacity were evaluated by gas chromatography coupled with tandem mass spectrometry. The precision and accuracy of the method showed a relative standard deviation lower than 10% and recoveries from 35 to 97%. Finally, the proposed method was employed for the determination of pesticide residues in coffee samples.

Screening of the bioactive compounds in Amphora coffeaeformis extract and evaluating its protective effects against deltamethrin toxicity in rats

Pyrethroids are synthetic chemicals similar to the pyrethrins, but more toxic to insects and mammals and persistent in the environment than pyrethrins. This study aimed to identify the bioactive compounds of Amphora coffeaeformis extract (ACE) and to determine their potential protective activity against deltamtherin (DEL) insecticide in rats. Six groups of male albino rats were treated for 4 weeks included the control group, ACE-treated group (772 mg/kg b.w.), DEL-exposed group (13.5 mg/kg b.w.), DEL plus ACE-treated group, and the groups treated with ACE for 14 days before or after DEL. At the end of treatment, blood and tissue samples were collected for biochemical assays. The GC-MS identified 18 compounds; most of them are fatty acid methyl ester, and the HPLC identified 8 polyphenols and significant amounts of vitamins A, C, B1, B2, B9, and E. The in vivo results revealed that DEL induced significant alterations in hematological and serum biochemical parameters, oxidative stress markers, proinflammatory cytokines, and NF-κB. ACE protects against DEL toxicity, and the protection was more pronounced in the groups treated with ACE plus DEL or ACE after DEL suggesting that ACE could be used for the prevention or the treatment of DEL toxicity. It could be concluded that ACE is a promising candidate for the production of bioactive compounds and should be considered in the pharmaceutical and food application.

Pesticide effects on fish cholinesterase variability and mean activity: A meta-analytic review

Fish cholinesterases (ChEs) - like acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) - are common biomarkers of environmental contamination due to their sensitivity to a variety of toxicants. To understand pesticide effects on fish ChEs mean activity and variability, we conducted a systematic review and meta-analyses. Our goal was to verify (i) if brain and muscle ChEs responded differently to pesticide exposure; (ii) how fish size and life stage (i.e., juvenile and adult) influence ChEs variability and mean activity; (iii) what type of pesticides (i.e., herbicide, insecticide, and fungicide) has the strongest effect, and if the analytical-grade compounds differ from commercial formulations; (iv) if increasing concentrations combined with prolonged exposure leads to stronger ChEs inhibition; and (v) how each class of pesticide affects these enzymes. We validated ChEs reliability as biomarkers and identified factors influencing their response. Regardless of tissue, BChE response was more variable than AChE, and no difference between their average activity was detected. The size of juvenile fish is an important factor affecting ChEs mean activity and variability, whereas pesticide had no significant effect on adult fish ChEs. Insecticides were stronger inhibitors compared to herbicides and fungicides. Analytical-grade compounds decreased ChEs mean activity to a higher degree than commercial formulations. The combined effect of concentration and time was only significant for fungicides and insecticides. Among classes, organophosphorus insecticides had the strongest effect on ChEs, followed by carbamates, organochlorines, and pyrethroids. Organophosphorus herbicides and oxazolidinones were the only herbicides to decrease ChEs mean activity significantly, and their effects were similar from those of pyrethroids and organochlorines. Additionally, our results identified research gaps, such as the small number of studies on fungicides, neonicotinoids and other relevant pesticides. These findings suggest future directions, which might help researchers identify robust cause-effect relationships between fish ChEs and pesticides.

Aircraft disinsection: what is the usefulness as a public health measure?

RATIONALE FOR REVIEW

Insecticide treatments in aircraft (termed 'aircraft disinsection') aim to support the containment of potentially disease-carrying vector insects. The introduction of non-endemic mosquito species is of concern as some mosquitoes can act as vectors of many serious human diseases. Expansion of vectors to previously non-endemic regions, extended flight networks and mosquito resistance to insecticides pose challenges to contemporary vector-control approaches. Despite established efficacy of aircraft disinsection in trials, there is increasing concern over its effectiveness and feasibility in flight operations, and its usefulness as a public health measure.

KEY FINDINGS

We explored the literature on disinsection through a narrative approach to obtain a pragmatic assessment of existing and future implementation challenges. We describe the shortcomings that hinder evaluation of the success of aircraft disinsection. These shortcomings include operational constraints that may impact effective treatment outcomes, lack of longitudinal data on pesticide exposure scenarios, lack of compliance mechanisms, pesticide resistance in mosquitoes, and limited evidence of the extent and type of mosquito species potentially transported via aircraft.

CONCLUSIONS AND RECOMMENDATIONS

Concerns about the introduction of non-endemic mosquito vectors reinforce the need for effective preventive measures. Import of disease vectors is likely to occur in the future under changing environmental and operational conditions. Optimal impact from disinsection requires appropriate deployment, commitment and use. The current system of evaluation is inadequate for producing the evidence needed for informed policy decisions. While utilizing the results of research into environmentally sustainable vector-control methods for use in aircraft, future approaches to aircraft disinsection require improved evidence of anticipated benefits and harms, reliable monitoring data on insecticide resistance, and must be supported by strong vector control at airports.

Salinity Changes the Dynamics of Pyrethroid Toxicity in Terms of Behavioral Effects on Newly Hatched Delta Smelt Larvae

Salinity can interact with organic compounds and modulate their toxicity. Studies have shown that the fraction of pyrethroid insecticides in the aqueous phase increases with increasing salinity, potentially increasing the risk of exposure for aquatic organisms at higher salinities. In the San Francisco Bay Delta (SFBD) estuary, pyrethroid concentrations increase during the rainy season, coinciding with the spawning season of Delta Smelt (Hypomesus transpacificus), an endangered, endemic fish. Furthermore, salinity intrusion in the SFBD is exacerbated by global climate change, which may change the dynamics of pyrethroid toxicity on aquatic animals. Therefore, examining the effect of salinity on the sublethal toxicity of pyrethroids is essential for risk assessments, especially during the early life stages of estuarine fishes. To address this, we investigated behavioral effects of permethrin and bifenthrin at three environmentally relevant concentrations across a salinity gradient (0.5, 2 and 6 PSU) on Delta Smelt yolk-sac larvae. Our results suggest that environmentally relevant concentrations of pyrethroids can perturb Delta Smelt larvae behavior even at the lowest concentrations (<1 ng/L) and that salinity can change the dynamic of pyrethroid toxicity in terms of behavioral effects, especially for bifenthrin, where salinity was positively correlated with anti-thigmotaxis at each concentration.

Parkinson's disease and pesticides: Are microRNAs the missing link?

Parkinson's disease (PD) is a common neurodegenerative disorder that leads to significant morbidity and decline in the quality of life. It develops due to loss of dopaminergic neurons in the substantia nigra pars compacta, and among its pathogenic factors oxidative stress plays a critical role in disease progression. Pesticides are a broad class of chemicals widely used in agriculture and households for the protection of crops from insects and fungi. Several of them have been incriminated as risk factors for PD, but the underlying mechanisms have yet to be fully understood. MicroRNAs (miRNAs) are small, non-coding RNA molecules that play an important role in regulating mRNA translation and protein synthesis. miRNA levels have been shown to be affected in several diseases as well. Since the studies on the association between pesticides and PD have yet to reach definitive conclusions, here we review recent evidence on deregulated microRNAs upon pesticide exposure, and attempt to find an overlap between miRNAs deregulated in PD and pesticides, as a missing link between the two, and enhance future research in this direction.

Peripubertal serum concentrations of organochlorine pesticides and semen parameters in Russian young men

BACKGROUND

Epidemiologic literature on the relation of organochlorine pesticides (OCPs) with semen quality among adult men has been inconclusive, and no studies have prospectively explored the association between peripubertal serum OCPs and semen parameters in young men.

OBJECTIVE

To evaluate prospective associations of peripubertal serum concentrations of hexachlorobenzene (HCB), β-hexachlorocylohexane (β-HCH), and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) with semen parameters among young Russian men.

METHODS

This prospective cohort study included 152 young men who enrolled in the Russian Children's Study (2003-2005) at age 8-9 years and were followed annually until young adulthood. HCB, β-HCH, and p,p'-DDE concentrations were measured at the CDC by mass spectrometry in serum collected at enrollment. Between 18 and 23 years, semen samples (n = 298) were provided for analysis of volume, concentration, and progressive motility; we also calculated total sperm count and total progressive motile count. Linear mixed models were used to examine the longitudinal associations of quartiles of serum HCB, β-HCH and p,p'-DDE with semen parameters, adjusting for total serum lipids, body mass index, smoking, abstinence time and baseline dietary macronutrient intake.

RESULTS

Lipid-adjusted medians (IQR) for serum HCB, βHCH and p,ṕ-DDE, respectively, were 150 ng/g lipid (102-243), 172 ng/g lipid (120-257) and 275 ng/g lipid (190-465). In adjusted models, we observed lower ejaculated volume with higher serum concentrations of HCB and βHCH, along with reduced progressive motility with higher concentrations of βHCH andp,ṕ-DDE. Men in the highest quartile of serum HCB had a mean (95% Confidence Interval, CI) ejaculated volume of 2.25 mL (1.89, 2.60), as compared to those in the lowest quartile with a mean (95% CI) of 2.97 mL (2.46, 3.49) (p = 0.03). Also, men in the highest quartile of serum p,ṕ-DDE had a mean (95% CI) progressive motility of 51.1% (48.6, 53.7), as compared to those in the lowest quartile with a mean (95% CI) of 55.1% (51.7, 58.5) (p = 0.07).

CONCLUSION

In this longitudinal Russian cohort study, peripubertal serum concentrations of selected OCPs were associated with lower ejaculated volume and progressive motility highlighting the importance of the peripubertal window when evaluating chemical exposures in relation to semen quality.

Bioaugmentation of Entomopathogenic Fungi for Sustainable Agriotes Larvae (Wireworms) Management in Maize

Soil microorganisms influence biotic and abiotic stress tolerance of crops. Most interactions between plant symbiotic and non-symbiotic soil microorganisms and plants occur in the rhizosphere and are sustained through plant exudation/rhizodeposition. Bioaugmentation, i.e., the introduction or amplification of certain plant beneficial microbes (e.g., entomopathogenic fungi) into the rhizosphere, could contribute to controlling insect crop pests and replacing chemical, environmentally unfriendly insecticides. Wireworms, the soil-burrowing larval stages of click beetles (Coleoptera: Elateridae), are major pests of crops including maize, wheat and potatoes, worldwide. Alternative strategies for controlling wireworms are needed because several chemical pesticides used successfully in the past are being phased out because of their ecotoxicity. Therefore, virulence to Agriotes lineatus L. wireworms and plant beneficial traits of entomopathogenic fungi were investigated in a series of laboratory experiments. Tested taxa included environmentally retrieved Metarhizium brunneum Petch. (two strains), M. robertsii Bisch., Rehner & Humber (Hypocreales: Clavicipitaceae), and Beauveria brongniartii (Sacc.) Petch. and commercially formulated B. bassiana (Bals.-Criv.) Vuill. (Cordycipitaceae) and Bacillus thuringiensis Berliner 1915 var. kurstaki. In-house reared larvae were dipped in conidial suspension, and maize and wheat seeds were coated with fungal conidia. Metarhizium brunneum strains 1154 and 1868 significantly increased wireworm mortality. Fungi were significantly more often re-isolated from maize than wheat rhizoplanes in laboratory assays. The strains tested were rarely isolated as endophytes. Metarhizium brunneum strain 1154 stimulated wheat growth, while M. robertsii 1880 stimulated maize growth, whereas M. brunneum 1868 and others did not affect root or shoot length or plant biomass significantly in laboratory settings. Metarhizium brunneum strain 1868, re-isolated most often from maize rhizoplane, caused the highest wireworm mortality. It was further evaluated whether M. brunneum 1868 can protect maize varieties FeroXXY, LG 34.90 and Chapalu from wireworm damage and promote plant growth at field conditions. Plants of all three varieties stemming from seeds treated with conidia of M. brunneum 1868 showed significantly less wireworm damage 3 to 4 weeks after sowing (5- to 6-leaf stage) resulting in a significantly higher initial maize stand. However, only in the variety LG 34.90 a significant increase of the maize stand was observed at harvest time.

Updates on molecular and environmental determinants of luteal progesterone production

Progesterone, a critical hormone in reproduction, is a key sex steroid in the establishment and maintenance of early pregnancy and serves as an intermediary for synthesis of other steroid hormones. Progesterone production from the corpus luteum is a tightly regulated process which is stimulated and maintained by multiple factors, both systemic and local. Multiple regulatory systems, including classic mediators of gonadotropin stimulation such as the cAMP/PKA pathway and TGFβ-mediated signaling pathways, as well as local production of hormonal factors, exist to promote granulosa cell function and physiological fine-tuning of progesterone levels. In this manuscript, we provide an updated narrative review of the known mediators of human luteal progesterone and highlight new observations regarding this important process, focusing on studies published within the last five years. We will also review recent evidence suggesting that this complex system of progesterone production is sensitive to disruption by exogenous environmental chemicals that can mimic or interfere with the activities of endogenous hormones.

Evaluation of dimethoate toxicity on fertilization and on embryonic development of Paracentrotus lividus (Lamarck, 1816)

Organophosphates are a large class of chemicals with anticholinesterase action insecticides. Dimethoate belongs to the class of organophosphates and it is used for agriculture purpose. Its main toxicological role in animals and humans is the inhibition of the activity of acetylcholinesterase. Although it is not considered genotoxic, carcinogenic and teratogen, there is evidence of increased pup mortality in developmental neurotoxicity studies. Since there is scant published literature about developmental toxicity, we investigated the adverse effects of dimethoate on fertilization and embryonic development in sea urchin (Paracentrotus lividus), a model organism widely used to assess the toxicity of contaminants on environmental matrices; so pesticide residues can be released into the environment, and could affect the health of organisms, including humans. Different solution of dimethoate (4 × 10^-3, 4 × 10^-4, 4 × 10^-5, 4 × 10^-6 and 4 × 10^-7 g/10 ml) have been tested on spermatozoa of P. lividus to evaluate the fertilizing ability of them when we added egg cells untreated. We demonstrated that dimethoate does not interfere with fertilizing ability of spermatozoa but egg cells fertilized by treated spermatozoa showed alterations in the segmentation planes as asymmetric and/or asynchronous cell divisions.

Nontransient third-degree heart block and persistent respiratory findings as sequelae of acute occupational exposure to pyrethroids insecticide

We present the case of a worker with occupational exposure to a pyrethroid insecticide who acutely developed nontransient third-degree heart block. In 2000, a 57-year-old male truck driver on his delivery route was accidentally exposed to pyrethroid insecticide being sprayed for West Nile virus containment. Both the driver and his vehicle were coated with the spray. The exposure was prolonged because he did not change his clothes until after his shift ended and he used the same contaminated truck for a week. Within days, he presented with a third-degree heart block, for which he was emergently treated, and a pacemaker was placed. He had no past history of arrhythmias. In the weeks thereafter, he also developed reactive airway dysfunction syndrome (RADS). In the second decade following the exposure, the patient replaced his pacemaker, confirming the permanent nature of his heart block. In addition to the persistence of his exposure-related RADS, he developed restrictive lung disease and was diagnosed with pulmonary interstitial fibrosis in the absence of established risk factors. The patient died in October 2019 from respiratory illness. Most previous reports of pyrethroid-related disorders are limited to acute exposures, in which transient symptoms predominate. To our knowledge, this is the first report of an exposed worker experiencing permanent third-degree heart block, as well as persistent respiratory findings, as possible short- and long-term sequelae of pyrethroid exposure.

Organochlorine pesticide levels in Greek patients with Parkinson's disease

Background

Parkinson’s disease (PD) is a neurodegenerative disease, mostly presenting with characteristic motor symptoms. Organochlorines (OC) are a class of widely-used pesticides that have been included among the list of environmental factors incriminated in PD pathogenesis. However, most studies reporting this association are based on questionnaires, and few have reported exposure data.

Aim

To examine the relationship between OC blood concentrations and PD risk.

Methods

In the present study, we studied the concentrations of 8 OC compounds (hexachlorobenzene, heptachlor, hepachlor epoxide, c-chlordane, a-chlordane, p,p’-DDE, DDD, DDT) in 104 Greek PD patients and 110 healthy controls.

Results

All substances studied were present in at least one sample. The most frequently detected (above the level of quantification) pesticides were p,p’-DDE (n = 214, 100 % of both groups) and hexachlorobenzene, HCB (n = 189, cases 46.5 %, controls 53.5 %). Higher levels of DDE were detected among PD patients in comparison to controls by using logistic regression analysis to control for confounders [Odds Ratio, OR (95 % confidence interval, C.I.)]: 2.592,(1.29–5.21)], whilst lower levels of HCB were detect among PD patients [OR,95 %CI:0.176(0.09−0.35)].

Conclusions

Our data suggest that exposure to specific OCs is related to the risk of PD. Further studies, using real exposure data, are needed in order to confirm and extend these findings.

Microbiota and Other Preventive Strategies and Non-genetic Risk Factors in Parkinson's Disease

The exact cause of Parkinson’s disease (PD), the second most prevalent neurodegenerative disease in modern societies, is still unknown. Many scientists point out that PD is caused by a complex interaction between different factors. Although the main risk factor is age, there are other influences, genetic and environmental, that individually or in combination may trigger neurodegenerative changes leading to PD. Nowadays, research remains focused on better understanding which environmental factors are related to the risk of developing PD and why. In line with the knowledge on evidence on exposures that prevent/delay PD onset or that impact on disease progression, the aims of this review were: (i) to comment on the non-genetic risk factors that mainly affect idiopathic PD; and (ii) to comment on seemingly reliable preventive interventions. We discuss both environmental factors that may affect the central nervous system (CNS) or the intestinal tract, and the likely mechanisms underlying noxious or protective actions. Knowledge on risk, protective factors, and mechanisms may help to envisage why nigral dopaminergic neurons are so vulnerable in PD and, eventually, to design new strategies for PD prevention and/or anti-PD therapy. This article reviews the variety of the known and suspected environmental factors, such as lifestyle, gut microbiota or pesticide exposition, and distinguishes between those that are harmful or beneficial for the PD acquisition or progression. In fact, the review covers one of the most novel players in the whole picture, and we address the role of microbiota on keeping a healthy CNS and/or on preventing the “side-effects” related to aging.

The Nrf2-Keap1 pathway: A secret weapon against pesticide persecution in Drosophila Kc cells

Nrf2-Keap1 pathway defends organisms against the detrimental effects of oxidative stress, and play pivotal roles in preventing xenobiotic-related toxicity. We designed experiments to explore and verify its role and function under deltamethrin (DM) stress. In experiments, DM was selected as the inducer, and Drosophila Kc cells were treated as the objects. The result showed the oxidative stress of cells proliferated in a very short time after DM treatment, reaching the maximum after one hour of treatment. The experimental data showed Nrf2 could be up-regulated and activated by DM which were manifested by the increase of Nrf2 mRNA, Nrf2 protein in the nucleus and the expression of detoxification enzyme genes. We further tested the activity of all groups, and found the survival rate of cells was basically proportional to the expression of Nrf2. Based on the above experimental results, Keap1 overexpression (K+), Nrf2 overexpression (N+) or interference (N-) cells were used to verified the relationship between Nrf2, cell survival and detoxification enzymes expression. We found the cell survival rate of N+ group was significantly higher than that of other groups and the expression of detoxification enzymes were increased compared to the control group. These results demonstrated that Nrf2 is related to cell detoxification and associated with the tolerance to DM. Our evidence suggested Nrf2 is a potential therapeutic target for oxidative stress and a potential molecular target gene of resistance control.

Cumulative exposure to organic pollutants of French children assessed by hair analysis

Children represent one of the most vulnerable parts of the population regarding the effects of pollutants exposure on health. In this study, hair samples were collected between October 2013 and August 2015 from 142 French children originating from different geographical areas (urban and rural) and analysed with a GC/MS-MS method, allowing for the detection of 55 biomarkers for pesticides and metabolites both persistent and non-persistent from different families, including: organochlorines, organophosphates, pyrethroids, azoles, dinitroanilines, oxadiazines, phenylpyrazoles and carboxamidas; 4 polychlorobiphenyls (PCBs) and 5 polybromodiphenylethers (PBDEs). The number of compounds detected in each sample ranged from 9 up to 37 (21 on average), which clearly highlighted the cumulative exposure of the children. The results also showed a wide range of concentration of the pollutants in hair (often more than 100 times higher in the most exposed child compared to the less exposed), suggesting significant disparities in the exposure level, even in children living in the same area. In addition to the detection of currently used chemicals, the presence of persistent organic pollutants (POPs) in children also suggests that the French population is still exposed to POPs nowadays. PCP, DEP, PNP, 3Me4NP, trans-Cl2CA, 3PBA, fipronil and fipronil sulfone, presented statistically significant higher concentration in the hair of boys compared to girls. PCP, PNP and 3Me4NP presented statistically significant higher concentration in younger children. Finally, this study also suggests that local environmental contamination would not be the main source of exposure, and that individual specificities (habits, diet…) would be the main contributors to the exposure to the pollutants analysed here. The present study strongly supports the relevance of hair for the biomonitoring of exposure and provides the first values of organic pollutant concentration in the hair of French children.

Pesticides With Potential Thyroid Hormone-Disrupting Effects: A Review of Recent Data

Plant Protection Products, more commonly referred to as pesticides and biocides, are used to control a wide range of yield-reducing pests including insects, fungi, nematodes, and weeds. Concern has been raised that some pesticides may act as endocrine disrupting chemicals (EDCs) with the potential to interfere with the hormone systems of non-target invertebrates and vertebrates, including humans. EDCs act at low doses and particularly vulnerable periods of exposure include pre- and perinatal development. Of critical concern is the number of pesticides with the potential to interfere with the developing nervous system and brain, notably with thyroid hormone signaling. Across vertebrates, thyroid hormone orchestrates metamorphosis, brain development, and metabolism. Pesticide action on thyroid homeostasis can involve interference with TH production and its control, displacement from distributor proteins and liver metabolism. Here we focused on thyroid endpoints for each of the different classes of pesticides reviewing epidemiological and experimental studies carried out both in in vivo and in vitro. We conclude first, that many pesticides were placed on the market with insufficient testing, other than acute or chronic toxicity, and second, that thyroid-specific endpoints for neurodevelopmental effects and mixture assessment are largely absent from regulatory directives.

Assessment of Cypermethrin Residues in Tobacco by a Bioelectric Recognition Assay (BERA) Neuroblastoma Cell-Based Biosensor

This study presents a bioelectric cell-based biosensor for the monitoring of the pyrethroid pesticide cypermethrin, a voltage-gated sodium channel blocker, in tobacco samples. For this purpose, neuroblastoma cells were used as biorecognition elements. The potential interference by the tobacco major alkaloid nicotine on the detection of cypermethrin was also studied. In addition, fluorescence microscopy revealed a specific pattern of neuroblastoma cell calcium efflux (Ca2+) after treatment with nicotine or cypermethrin. Finally, actual field-derived tobacco extracts were used for assessing matrix effects on the biosensor’s performance. The biosensor could detect cypermethrin in concentrations up to 1.5 μg mL−1 without being influenced by the presence of nicotine and possibly other tobacco alkaloids. Though not selective for cypermethrin, the neuroblastoma-based biosensor system appears to be a promising alternative to laborious analysis methodologies for rapid, high throughput and cost-efficient screening of this pyrethroid in tobacco samples in the near future.

A Multiomics Study To Unravel the Effects of Developmental Exposure to Endosulfan in Rats: Molecular Explanation for Sex-Dependent Effects

Exposure to low levels of environmental contaminants, including pesticides, induces neurodevelopmental toxicity. Environmental and food contaminants can reach the brain of the fetus, affecting brain development and leading to neurological dysfunction. The pesticide endosulfan is a persistent pollutant, and significant levels still remain detectable in the environment although its use is banned in some countries. In rats, endosulfan exposure during brain development alters motor activity, coordination, learning, and memory, even several months after uptake, and does so in a sex-dependent way. However, the molecular mechanisms driving these effects have not been studied in detail. In this work, we performed a multiomics study in cerebellum from rats exposed to endosulfan during embryonic development. Pregnant rats were orally exposed to a low dose (0.5 mg/kg) of endosulfan, daily, from gestational day 7 to postnatal day 21. The progeny was evaluated for cognitive and motor functions at adulthood. Expression of messenger RNA and microRNA genes, as well as protein and metabolite levels, were measured on cerebellar samples from males and females. An integrative analysis was conducted to identify altered processes under endosulfan effect. Effects between males and females were compared. Pathways significantly altered by endosulfan exposure included the phosphatidylinositol signaling system, calcium signaling, the cGMP-PKG pathway, the inflammatory and immune system, protein processing in the endoplasmic reticulum, and GABA and taurine metabolism. Sex-dependent effects of endosulfan in the omics results that matched sex differences in cognitive and motor tests were found. These results shed light on the molecular basis of impaired neurodevelopment and contribute to the identification of new biomarkers of neurotoxicity.