Reproductive effects of two neonicotinoid insecticides on mouse sperm function and early embryonic development in vitro

The neonicotinoid, imidacloprid, disrupt the chicken sperm quality through calcium efflux

Imidacloprid (IMI), an insecticide from the neonicotinoid group widely used in agriculture, has drawn attention due to its potential harmful effects on non-target species, including bird populations. In the present work, we investigated the effect of IMI on avian semen by in vitro exposure of rooster spermatozoa to this pesticide. The semen was collected twice a week. Samples collected on one day were pooled and incubated with the following IMI concentrations: 0 mM, 0.5 mM, 5 mM, 10 mM, and 50 mM at 36°C for 3 h. Comprehensive semen analysis was carried out after 1 h and 3 h of incubation, evaluating sperm motility parameters with the CASA system and using flow cytometry to assess membrane integrity, mitochondrial activity, acrosome integrity, chromatin structure, intracellular calcium level and apoptosis markers such as: early apoptosis and caspase activation and lipid peroxidation. The results of the first experiment suggest that low concentrations of IMI have a different effect on sperm motility compared to higher concentrations. In IMI samples, we also observed a lower percentage of cells with a high level of calcium ions compared to the control, and a lower level of lipid peroxidation. We concluded that IMI may act as a blocker of calcium channels, preventing the influx of these ions into the cell. To confirm this mechanism, we conducted a second experiment with calcium channel blockers: SNX 325, MRS-1845, and Nifedipine. The results of this experiment confirmed that the mechanism of action of IMI largely relies on the blockade of calcium channels in rooster sperm. Blocking the influx of calcium ions into the cell prevents the formation of Ca²⁺-dependent pores, thereby preventing an increase in cell membrane permeability, ultimately blocking early apoptosis and lipid peroxidation in chicken spermatozoa.

Typical neonicotinoids and organophosphate esters, but not their metabolites, adversely impact early human development by activating BMP4 signaling

Recent studies have highlighted the presence of potentially harmful chemicals, such as neonicotinoids (NEOs) and organophosphate esters (OPEs), in everyday items. Despite their potential threats to human health, these dangers are often overlooked. In a previous study, we discovered that NEOs and OPEs can negatively impact development, but liver metabolism can help mitigate their harmful effects. In our current research, our objective was to investigate the toxicity mechanisms associated with NEOs, OPEs, and their liver metabolites using a human embryonic stem cell-based differentiation model that mimics early embryonic development. Our transcriptomics data revealed that NEOs and OPEs significantly influenced the expression of hundreds of genes, disrupted around 100 biological processes, and affected two signaling pathways. Notably, the BMP4 signaling pathway emerged as a key player in the disruption caused by exposure to these pollutants. Both NEOs and OPEs activated BMP4 signaling, potentially impacting early embryonic development. Interestingly, we observed that treatment with a human liver S9 fraction, which mimics liver metabolism, effectively reduced the toxic effects of these pollutants. Most importantly, it reversed the adverse effects dependent on the BMP4 pathway. These findings suggest that normal liver function plays a crucial role in detoxifying environmental pollutants and provides valuable experimental insights for addressing this issue.

Developmental toxicity assessment of neonicotinoids and organophosphate esters with a human embryonic stem cell- and metabolism-based fast-screening model

In recent years, neonicotinoids (NEOs) and organophosphate esters (OPEs) have been widely used as substitutes for traditional pesticides and brominated flame-retardants, respectively. Previous studies have shown that those compounds can be frequently detected in environmental and human samples, are able to penetrate the placental barrier, and are toxic to animals. Thus, it is reasonable to speculate that NEOs and OPEs may have potential adverse effects in humans, especially during development. We employed a human embryonic stem cell differentiation- and liver S9 fraction metabolism-based fast screening model to assess the potential embryonic toxicity of those two types of chemicals. We show that four NEO and five OPE prototypes targeted mostly ectoderm specification, as neural ectoderm and neural crest genes were down-regulated, and surface ectoderm and placode markers up-regulated. Human liver S9 fraction's treatment could generally reduce the effects of the chemicals, except in a few specific instances, indicating the liver may detoxify NEOs and OPEs. Our findings suggest that NEOs and OPEs interfere with human early embryonic development.

Non-acute exposure of neonicotinoids, health risk assessment, and evidence integration: a systematic review

Neonicotinoid pesticides are utilized against an extensive range of insects. A growing body of evidence supports that these neuro-active insecticides are classified as toxicants in invertebrates. However, there is limited published data regarding their toxicity in vertebrates and mammals. the current systematic review is focused on the up-to-date knowledge available for several neonicotinoid pesticides and their non-acute toxicity on rodents and human physiology. Oral lethal dose 50 (LD50) of seven neonicotinoids (i.e. imidacloprid, acetamiprid, clothianidin, dinotefuran, thiamethoxam, thiacloprid, and nitenpyram) was initially identified. Subsequently, a screening of the literature was conducted to collect information about non-acute exposure to these insecticides. 99 studies were included and assessed for their risk of bias and level of evidence according to the Office of Health and Translation (OHAT) framework. All the 99 included papers indicate evidence of reproductive toxicity, hepatotoxicity, nephrotoxicity, neurotoxicity, immunotoxicity, and oxidative stress induction with a high level of evidence in the health effect of rodents and a moderate level of evidence for human health. The most studied type of these insecticides among 99 papers was imidacloprid (55 papers), followed by acetamiprid (22 papers), clothianidin (21 papers), and thiacloprid (11 papers). While 10 of 99 papers assessed the relationship between clothianidin, thiamethoxam, dinotefuran, and nitenpyram, showing evidence of liver injury, dysfunctions of oxidative stress markers in the reproductive system, and intestinal toxicity. This systematic review provides a comprehensive overview of the potential risks caused by neonicotinoid insecticides to humans and rodents with salient health effects. However, further research is needed to better emphasize and understand the patho-physiological mechanisms of these insecticides, taking into account various factors that can influence their toxicity.

Long-lasting developmental effects in rat offspring after maternal exposure to acetamiprid in the drinking water during gestation

Neonicotinoids (NNTs) are a class of insecticides proposed to be safe for pest control in urban, suburban, and agricultural applications. However, little is known about their developmental effects after repeated low-dose exposures during gestation. Here, we tested a dose considered subthreshold for maternal toxicity in rats (6 mg/kg/day) by assessing several morphological, biochemical, and neurobehavioral features in preterm fetuses and developing pups after maternal administration of the NTT acetamiprid (ACP) dissolved in the drinking water during gestational days (GD) 2-19. The exploratory evaluation included monitoring maternal body weight gain, fetal viability, body weight and sex ratio, cephalic length, neonatal body weight and sex ratio, metabolic enzymes in the placenta, maternal blood and fetal liver, and anogenital distance and surface righting response during infancy. We also used the circling training test to study the integrity of the associative-spatial-motor response in adolescence. Results showed no consistent findings indicating maternal, reproductive or developmental toxicity. However, we found ACP effects on maternal body weight gain, placental butyrylcholinesterase activity, and neurobehavioral responses, suggestive of a mild toxic action. Thus, our study showed a trend for developmental susceptibility at a dose so far considered subtoxic. Although the ACP concentration in environmental samples of surface water and groundwater has been mostly reported to be much lower than that used in our study, our results suggest that the ACP point of departure used in current guidelines aimed to prevent developmental effects may need to be verified by complementary sensitive multiple-endpoint testing in the offspring.

Fano resonance-integrated metal nanoparticles' enhanced sensing for pesticide detection

The combined application of metasurface and terahertz (THz) time-domain spectroscopy techniques has received considerable attention in the fields of sensing and detection. However, to detect trace samples, the THz wave must still be enhanced locally using certain methods to improve the detection sensitivity. In this study, we proposed and experimentally demonstrated a fano resonance metasurface-based silver nanoparticles (FaMs-AgNPs) sensor. AgNPs can enhance the sensitivity of the sensor by generating charge accumulation and inducing localized electric field enhancement through the tip effect, thereby enhancing the interaction between the THz waves and analytes. We investigated the effects of four different contents of AgNPs, 10 µl, 20 µl, 30 µl and 40 µl, on the detection of acetamiprid. At 30 µl of AgNPs, the amplitude change of the FaMs-AgNPs sensor was more pronounced and the sensitivity was higher, which could detect acetamiprid solutions as low as 100 pg/ml. The FaMs-AgNPs sensor has the advantages of a simple structure, easy processing, and excellent sensing performance, and has a great potential application value in the field of THz trace detection and other fields.

Determination of biochemical and histopathological changes on testicular and epididymis tissues induced by exposure to insecticide Imidacloprid during postnatal development in rats

BACKGROUND

Imidacloprid is a neonicotinoid insecticide belonging to the chloronicotinyl nitroguanidine chemical family. Toxicity of IMD for mammals in scientific studies has shown high mutagenic, immunotoxic, teratogenic and neurotoxic effects. The present study was designed to assess the toxic effects of imidacloprid (IMD) on the testicular and epididymis tissues as well as testosterone levels of neonatal male rats.

METHODS

Neonatal male rats from postnatal day (PND) 1 to PND 26 were consecutively administered with different concentrations of IMD (1, 5 and 10 mg/kg) subcutaneously. The effect of IMD on body and organ weight, lipid profile, histopathological alterations, oxidative stress and altered testosterone levels were assessed in the testis and plasma.

RESULTS

The results of body weight gain showed a significant difference in group 4 (10 mg/kg) animals as compared to the control. A significant increase in total cholesterol and triglycerides, while a decrease in high-density lipoprotein concentrations was evident. Similarly, a significant decrease in concentrations of antioxidant enzymes (CAT and SOD) among all the IMD-treated groups was evident, when compared to the control. Increased production of ROS was also noticed in the highest-dose treatment group. Further, we observed that IMD-treated rats indicated histopathological changes in the testis and epididymis along with a significant decrease in the plasma testosterone concentrations among IMI-treated groups in contrast to the control. Histological examination of the testis of IMD-treated neonatal male rats also showed decreased spermatogenesis in the treated groups when compared to the control. Furthermore, an increase in lumen diameter and a decrease in epithelial height of seminiferous tubules were also observed in IMD-treated rats in comparison with the control.

CONCLUSION

It is concluded that sub-chronic exposure to IMD in neonatal male rats may induce histopathological changes in reproductive tissues and damage normal testicular functions via inducing oxidative stress, decrease in body weight, disturbing normal blood lipid profile and testosterone concentration. IMD exposure can induce pathophysiological effects calls for further evaluation of this widely used insecticide.

Chronic Paternal/Maternal Exposure to Environmental Concentrations of Imidacloprid and Thiamethoxam Causes Intergenerational Toxicity in Zebrafish Offspring

Imidacloprid (IMI) and thiamethoxam (THM) are ubiquitous in aquatic ecosystems. Their negative effects on parental fish are investigated while intergenerational effects at environmentally relevant concentrations remain unclear. In this study, F0 zebrafish exposed to IMI and THM (0, 50, and 500 ng L-1) for 144 days post-fertilization (dpf) was allowed to spawn with two modes (internal mating and cross-mating), resulting in four types of F1 generations to investigate the intergenerational effects. IMI and THM affected F0 zebrafish fecundity, gonadal development, sex hormone and VTG levels, with accumulations found in F0 muscles and ovaries. In F1 generation, paternal or maternal exposure to IMI and THM also influenced sex hormones levels and elevated the heart rate and spontaneous movement rate. LncRNA-mRNA network analysis revealed that cell cycle and oocyte meiosis-related pathways in IMI groups and steroid biosynthesis related pathways in THM groups were significantly enriched in F1 offspring. Similar transcriptional alterations of dmrt1, insl3, cdc20, ccnb1, dnd1, ddx4, cox4i1l, and cox5b2 were observed in gonads of F0 and F1 generations. The findings indicated that prolonged paternal or maternal exposure to IMI and THM could severely cause intergenerational toxicity, resulting in developmental toxicity and endocrine-disrupting effects in zebrafish offspring.

Proteomic responses in the human dopaminergic LUHMES cell line to imidacloprid and its metabolites imidacloprid-olefin and desnitro-imidacloprid

Neonicotinoids (neonics) are amongst the most commonly used class of pesticides globally. In the United States, imidacloprid (IMI) is extensively used for agriculture and in other common applications such as house-hold pest control. Regular exposure to IMI, and several of its known metabolites including IMI-olefin and desnitro-imidacloprid (DN-IMI), has been shown to be harmful to many organisms including mammals, birds, and fish. Studies show that neonics bind human nicotinicacetylcholine receptors (nAChRs) and cause cellular toxicity. In the dopaminergic Lund human mesencephalic (LUHMES) cell line, IMI and other neonics (10-100 μM) have been recently shown to activate intracellular calcium signaling through nAChRs. Thus, we examined proteomic responses of LUHMES cells to a 48-h treatment with 50 μM IMI, IMI-olefin, or DN-IMI. Our findings show differential effects of these neonics on cellular protein expression. Bioinformatic analysis of significantly altered proteins indicates an effect of IMI, IMI-olefin, and DN-IMI on protein synthesis and ribosomal function. These findings suggest a role for protein synthesis and transcriptional regulation in neonic-mediated dopaminergic neurotoxicity.

Changing on the Concentrations of Neonicotinoids in Rice and Drinking Water through Heat Treatment Process

Neonicotinoids (NEOs) have become the most widely used insecticides in the world since the mid-1990s. According to Chinese dietary habits, rice and water are usually heated before being consumed, but the information about the alteration through the heat treatment process is very limited. In this study, NEOs in rice samples were extracted by acetonitrile (ACN) and in tap water, samples were extracted through an HLB cartridge, then, a high-performance liquid chromatography system and a triple quadrupole mass spectrometry (HPLC-MS/MS) were applied for target chemical analysis. The parents of NEOs (p-NEOs) accounted for >99% of the total NEOs mass (∑NEOs) in both uncooked (median: 66.8 ng/g) and cooked (median: 41.4 ng/g) rice samples from Guangdong Province, China, while the metabolites of NEOs (m-NEOs) involved in this study accounted for less than 1%. We aimed to reveal the concentration changes of NEOs through heat treatment process, thus, several groups of rice and water samples from Guangdong were cooked and boiled, respectively. Significant (p < 0.05) reductions in acetamiprid, imidacloprid (IMI), thiacloprid, and thiamethoxam (THM) have been observed after the heat treatment of the rice samples. In water samples, the concentrations of THM and dinotefuran decreased significantly (p < 0.05) after the heat treatment. These results indicate the degradation of p-NEOs and m-NEOs during the heat treatment process. However, the concentrations of IMI increased significantly in tap water samples (p < 0.05) after heat treatment process, which might be caused by the potential IMI precursors in those industrial pesticide products. The concentrations of NEOs in rice and water can be shifted by the heat treatment process, so this process should be considered in relevant human exposure studies.

Discovery and structure-activity relationship of Morita-Baylis-Hillman adducts as larvicides against dengue mosquito vector, Aedes aegypti (Diptera: Culicidae)

Neglected tropical diseases (NTDs) have become a significant public health problem worldwide, notably the life-threatening dengue hemorrhagic fever borne by the Aedes aegypti mosquito. Thus, mosquito vector control measures remain essential in public health vector surveillance and control to combat Aedes-borne infections. Therefore, a series of MBH adducts were synthesized and assessed towards the fourth instar mosquito larvae, Aedes aegypti, along with the preliminary structure-activity relationship (SAR). Noteworthy, this compound class might be synthetized by an efficient eco-friendly synthesismethod and a rapid route for the synthesis of commercial larvicide through a single synthetic step. The bioassays showed that this compound class is a promising larvicide to control Aedes aegypti mosquito larvae, mainly 3g, with an LC₅₀ of 41.35 µg/mL, which was higher than evaluated positive controls. Nevertheless, it is a viable larvicidalhit candidate for further hit-to-leadproperties optimization of its biphenyl backbone scaffold with enhanced insecticidalbioactivity. Moreover, scanning electron microscopy analysis suggested a disruption of the osmoregulatory/ionoregulatory functions by the complete deterioration of the terminal exoskeleton hindgut and anal papillae. Therefore, this new study shows the larvicidal efficacy of the tested compounds against the Aedes aegypti larvae.

First evidence of neonicotinoid insecticides in human bile and associated hepatotoxicity risk

Neonicotinoids (NEOs) are widely applied in agricultural lands and are widespread in different environments, accelerating threats to ecosystems and human health. A number of in vitro/in vivo studies have reported adverse effects of NEOs on mammalian health, but the link between NEO exposure and toxic effects on human liver remains unclear. We randomly recruited 201 participants and quantified eight commercialized NEOs in bile. High frequency and concentration of detection indicate low degradation of human liver on NEOs. The main NEOs are nitenpyram and dinotefuran, which contribute to about 86% of the total residual levels of eight NEOs, due to the highest solubility in bile and are not degraded easily in liver. In contrast, imidacloprid and thiacloprid are major compounds in human blood, according to previous studies, suggesting that individual NEOs behave differently in blood and bile distribution. There was no statistical difference in NEO residues between cancer and non-cancer participants and among the different participant demographics (e.g., age, gender, and body mass index). The serum hematological parameters -bile acid, total bilirubin, cholesterol and alkaline phosphatase -were positively correlated with individual NEO concentrations, suggesting that NEO exposure affects liver metabolism and even enterohepatic circulation. The study first examined the NEO residues in human bile and provided new insights into their bioavailability and hepatoxicity risk.

Single and mixed exposure to distinct groups of pesticides suggests endocrine disrupting properties of imidacloprid in zebrafish embryos

Due to their selective toxicity to insects, nicotinoid compounds have been widely used to control pests in crops and livestock around the world. However, despite the advantages presented, much has been discussed about their harmful effects on exposed organisms, either directly or indirectly, with regards to endocrine disruption. This study aimed to evaluate the lethal and sublethal effects of imidacloprid (IMD) and abamectin (ABA) formulations, separately and combined, on zebrafish (Danio rerio) embryos at different developmental stages. For this, Fish Embryo Toxicity (FET) tests were carried out, exposing two hours post-fertilization (hpf) zebrafish to 96 hours of treatments with five different concentrations of abamectin (0.5-11.7 mg L^-1), imidacloprid (0.0001-1.0 mg L^-1), and imidacloprid/abamectin mixtures (LC₅₀/2 - LC₅₀/1000). The results showed that IMD and ABA caused toxic effects in zebrafish embryos. Significant effects were observed regarding egg coagulation, pericardial edema, and lack of larvae hatching. However, unlike ABA, the IMD dose-response curve for mortality had a bell curve display, where medium doses caused more mortality than higher and lower doses. These data demonstrate the toxic influence of sublethal IMD and ABA concentrations on zebrafish, suggesting that these compounds should be listed for river and reservoir water-quality monitoring.

Reproductive Effects of S. boulardii on Sub-Chronic Acetamiprid and Imidacloprid Toxicity in Male Rats

The potential health-promoting effects of probiotics against intoxication by pesticides is a topic of increasing commercial interest with limited scientific evidence. In this study, we aimed to investigate the positive effects of probiotic Saccharomyces boulardii on the male reproductive system under low dose neonicotinoid pesticide exposure conditions. We observed that acetamiprid and imidacloprid caused a degeneration and necrosis of the spermatocytes in the tubular wall, a severe edema of the intertubular region and a hyperemia. This was concomittant to increased levels of 8-hydroxy-2'-deoxyguanosine reflecting oxidative stress, and an increase in caspase 3 expression, reflecting apoptosis. According to our results, Saccharomyces boulardii supplementation mitigates these toxic effects. Further in vivo and clinical studies are needed to clarify the molecular mechanisms of protection. Altogether, our study reinforces the burden of evidence from emerging studies linking the composition of the gut microbiome to the function of the reproductive system.

Environmental occurrence, toxicity concerns, and biodegradation of neonicotinoid insecticides

Neonicotinoids (NEOs) are fourth generation pesticides, which emerged after organophosphates, pyrethroids, and carbamates and they are widely used in vegetables, fruits, cotton, rice, and other industrial crops to control insect pests. NEOs are considered ideal substitutes for highly toxic pesticides. Multiple studies have reported NEOs have harmful impacts on non-target biological targets, such as bees, aquatic animals, birds, and mammals. Thus, the remediation of neonicotinoid-sullied environments has gradually become a concern. Microbial degradation is a key natural method for eliminating neonicotinoid insecticides, as biodegradation is an effective, practical, and environmentally friendly strategy for the removal of pesticide residues. To date, several neonicotinoid-degrading strains have been isolated from the environment, including Stenotrophomonas maltophilia, Bacillus thuringiensis, Ensifer meliloti, Pseudomonas stutzeri, Variovorax boronicumulans, and Fusarium sp., and their degradation properties have been investigated. Furthermore, the metabolism and degradation pathways of neonicotinoids have been broadly detailed. Imidacloprid can form 6-chloronicotinic acid via the oxidative cleavage of guanidine residues, and it is then finally converted to non-toxic carbon dioxide. Acetamiprid can also be demethylated to remove cyanoimine (=N-CN) to form a less toxic intermediate metabolite. A few studies have discussed the neonicotinoid toxicity and microbial degradation in contaminated environments. This review is focused on providing an in-depth understanding of neonicotinoid toxicity, microbial degradation, catabolic pathways, and information related to the remediation process of NEOs. Future research directions are also proposed to provide a scientific basis for the risk assessment and removal of these pesticides.

The Effect of Increasing the Dose of Acetamiprid and Dichlorvos Pesticides on the Reproductive Performance of Laboratory Mice

Background

Pesticides are widely used around the world. However, these chemicals are being used more frequently and at increased doses in underdeveloped and developing countries. Although the hazard of pesticides has been studied in ecological fields, the effect of residual amounts of these compounds on the physiological processes of the body has always been debated.

Materials and Methods

In this experimental study, 45 greenhouse cucumber plants were sprayed with dichlorvos and acetamiprid pesticides in concentrations of twofold (acetamiprid 500 g/1000 L and dichlorvos 4 L/1000 L) and threefold of the recommended dose. After 24 h, the residual amount was obtained. To evaluate the residual effect of the mentioned pesticides, an equivalent of this residue was added to the drinking water of 105 mice.

Results

Pesticide residues were obtained for twofold and threefold concentrations of the recommended dose, 1.5 and 2.5 (mg/kg cucumber) for acetamiprid and 0.5 and 1 (mg/kg cucumber) for dichlorvos, respectively. Application of these chemicals at higher doses not only significantly reduced the body weight, food consumption, testosterone production, testicular germ cells and embryo numbers, but also increased the levels of follicle-stimulating hormone and luteinizing hormone in mice.

Conclusions

The emergence of biological disorders and reducing reproductive potential in male mice can be attributed to the addition of pesticides to their drinking water. Therefore, to reduce the hazards caused by insecticides, it is recommended to familiarize farmers with the harmful effects of overdose of pesticides and monitoring the residuals in agricultural products.

Detection of Changes in Monoamine Neurotransmitters by the Neonicotinoid Pesticide Imidacloprid Using Mass Spectrometry

Monoamine neurotransmitters (MAs), including dopamine (DA) and serotonin (5-HT), regulate brain functions such as behavior, memory, and learning. Neonicotinoids are pesticides that are being used more frequently. Neonicotinoid exposure has been observed to produce neurological symptoms, such as altered spontaneous movements and anxiety-like behaviors, which are suspected to be caused by altered MA levels. However, current neurotoxicity tests are not sufficiently sensitive enough to make these determinations. In this study, we performed some behavior tests, and derivatization reagents to improve the ionization efficiency, which was applied to liquid chromatography mass spectrometry (LC-MS/MS) to reveal the effect of neonicotinoid administration on MAs in the brain. We orally administered the neonicotinoid imidacloprid (0, 10, and 50 mg/kg body weight) to C57BL/6NCrSlc mice. In the behavior tests, a decrease in activity was observed. The LC-MS/MS quantification of MAs in various brain regions showed a decrease in some MA levels in the olfactory bulb and the striatum. These results showed, for the first time, that even a low dose of imidacloprid could alter MA levels in various parts of the brain.

Determination of 20 Neonicotinoid Insecticides and Their Metabolites in Infant Foods by a Modified QuEChERS Method Combined with HPLC-MS/MS

A rapid, effective, and reliable method for the simultaneous detection of 20 neonicotinoids and their metabolites in infant foods has been developed using liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). To improve the accuracy and precision of the method, different extraction solvents, extraction methods, and adsorbents were evaluated to achieve a better recovery and clean-up effect. Under optimized conditions, the samples were extracted with acetic acid acidified acetonitrile/ethyl acetate by ultrasonication, and then were cleaned with reduced graphene oxide@Fe3O4 (rGO@Fe3O4) and primary and secondary amine (PSA) through a QuEChERS step. A matrix-matched calibration method was applied for quantification. Relative standard deviations were all <15% for intraday and interday precision. The values of limit of detection and limit of quantification were ranging from 0.02–0.35 μg·kg−1 and 0.1–1.0 μg·kg−1, respectively. The presented method was applied to the analysis of real samples.

High spatial resolved cropland coverage and cultivation category determine neonicotinoid distribution in agricultural soil at the provincial scale

Croplands are experiencing increasing neonicotinoid pollution and ecological health problems, which are especially widely applied in China. However, the large regional scale distribution of neonicotinoids and the key factors have seldom been determined. We show that the total residual concentration of neonicotinoids ranged from 13.4 to 157 ng/g with an average level of 75.8 ng/g and imidacloprid which was the dominant compound ranged from 10.4 to 81.3 ng/g during 2017-2021 in the Yangtze River Delta, China. In comparison, the neonicotinoid residues detected here were mostly higher than those in other regions. We further show that the 1-km spatial resolution cropland coverage (78.0%) and crop type (18.1%) predominantly contributed to the large spatial variation of neonicotinoids after adjusting for the factors including temperature, soil pH, soil moisture, and precipitation via automatic linear regression modeling at the provincial scale. Additional analyses revealed that tea croplands had significantly lowest concentration and fruit fields had the highest level due to the different application methods. Our findings provide new insight into key factors quantifying the high spatial resolved distribution of neonicotinoids and urgently call for reasonable application methods against rapidly growing ecology threats from neonicotinoid pollution in China.

Exposure assessment of neonicotinoid insecticides and their metabolites in Chinese women during pregnancy: A longitudinal study

Neonicotinoid insecticides (NNIs) are the most widely used insecticides globally and ubiquitous in the environment, which has led to widespread human exposure. However, studies on internal exposure levels of NNIs and their metabolites in pregnant women are scarce. In this study, we measured nine parent NNIs and ten main metabolites in 1224 urine samples donated by 408 pregnant women at three trimesters. In the urine samples, the unadjusted vs. specific gravity (SG) adjusted median concentrations and detection frequencies (DFs) of desmethyl-acetamiprid (DM-ACE; 1.01 vs. 1.08 ng/mL; DF: 99.7%), 5-hydroxy-imidacloprid (5-hydroxy-IMI; 0.54 vs. 0.56 ng/mL; 98.5%), imidacloprid-olefin (IMI-olefin; 0.41 vs. 0.44 ng/mL; 99.3%), and desnitro-imidacloprid (DN-IMI; 0.12 vs. 0.12 ng/mL; 90.4%) were higher than their corresponding parent NNIs, acetamiprid (ACE; <0.01 vs. <0.01 ng/mL; 26.4%) and imidacloprid (IMI; 0.04 vs. 0.04 ng/mL; 69.9%). The unadjusted and SG-adjusted median concentrations of clothianidin (CLO), thiamethoxam (THM), and desmethyl-clothianidin (DM-CLO) were 0.05 vs. 0.07, 0.05 vs. 0.06, and 0.04 vs. 0.05 ng/mL, with the DFs of 61.0%, 57.5%, and 75.7%, respectively. The cumulative exposure level, imidacloprid-equivalent total NNIs (IMI_eq), was generated by the relative potency factor approach considering the toxic effects of NNIs and their metabolites. The unadjusted IMI_eq varied from 0.17 ng/mL (SG-adjusted: 0.20) to 1969 ng/mL (SG-adjusted: 1817) with a median of 14.1 ng/mL (SG-adjusted: 14.1). A decreased trend was observed in urinary NNIs and their metabolites throughout the three trimesters. Maternal age, educational level, and household income were related to the concentrations of NNIs and their metabolites. DM-ACE, 5-hydroxy-IMI, and IMI-olefin were significantly lower in winter than in autumn; DN-IMI, THM, CLO, and DM-CLO were significantly higher in both summer and autumn than in winter. The maximum estimated daily intake of IMI_eq [34.8 μg/kg-body weight (bw)/d] was lower than the chronic reference dose of IMI (57 μg/kg-bw/d) currently recommended by the United States Environmental Protection Agency. Human health risk of exposure to NNIs and their main metabolites warranted further studies.

The Neonicotinoid Thiacloprid Interferes with the Development, Brain Antioxidants, and Neurochemistry of Chicken Embryos and Alters the Hatchling Behavior: Modulatory Potential of Phytochemicals

Simple Summary

The present experiment was performed to investigate the toxic impact of thiacloprid (TH) on the brain of developing chicken embryos and also to measure its influence on the behavioral responses of hatchlings. The role of chicoric acid (CA) and rosmarinic acid (RA) in modulating the resulted effects was also investigated. TH resulted neurotoxic to chicken embryos and possibly neurotoxic to embryos of other vertebrates. Moreover, CA and RA exerted both an antioxidant and a neuroprotective effect on embryos.

Abstract

The present experiment was performed to investigate the toxic impact of thiacloprid (TH) on the brain of developing chicken embryos and also to measure its influence on the behavioral responses of hatchlings. The role of chicoric acid (CA) and rosmarinic acid (RA) in modulating the resulted effects was also investigated. The chicken eggs were in ovo inoculated with TH at different doses (0.1, 1, 10, and 100 ug/egg). TH increased the mortality and abnormality rates and altered the neurochemical parameters of exposed embryos dose-dependently. TH also decreased the brain level of monoamines and amino acid neurotransmitters and decreased the activities of acetylcholine esterase (AchE) and Na⁺/K⁺-ATPase. The brain activity of catalase (CAT) and superoxide dismutase (SOD) was diminished with downregulation of their mRNA expressions in the brain tissue. When TH was co-administered with CA and RA, the toxic impacts of the insecticide were markedly attenuated, and they showed a complementary effect when used in combination. Taken together, these findings suggested that TH is neurotoxic to chicken embryos and is possibly neurotoxic to embryos of other vertebrates. The findings also demonstrated the antioxidant and neuroprotective effects of CA and RA. Based on the present findings, the CA and RA can be used as invaluable ameliorative of TH-induced toxicity.

Serum concentrations of neonicotinoids and their characteristic metabolites in elderly population from South China: Association with osteoporosis

Neonicotinoids (NEOs) are extensively applied in global agricultural production for pest control but have adverse effects on human health. In this study, the concentrations of six NEOs and three characteristic metabolites were investigated by collecting 200 serum samples from an elderly population in China. Results showed that the NEOs and their metabolites were widely detected (89%-98 %) in the serum samples from the osteoporosis (OP) (n = 120) and non-OP (n = 80) population, and their median concentrations ranged from 0.04 ng/mL to 5.99 ng/mL and 0.01 ng/mL to 2.02 ng/mL, respectively. N-desmethyl-acetamiprid (ACE-dm) was the most abundant NEOs in the serum samples. Gender-related differences were found in concentrations of most NEOs and their metabolites in serum, with males having higher target analytes than females. Significantly (p < 0.05) positive correlations were observed among most NEO concentrations, suggesting that exposure source of these substances is common or related. However, associations between the concentrations of characteristic metabolites and their corresponding NEOs were insignificant, probably because the exogenous intake are the primary sources of metabolites of NEOs instead of the internal biotransformation. The associations between NEO concentrations (i.e., ACE-dm, dinotefuran, and olefin-imidacloprid) and OP (OR = 2.33-6.92, 95 % CI = 0.37-16.9, p-trend < 0.05) indicate that NEO exposure is correlated with increased odds of prevalent OP. This study is the first to document the profiles of NEOs and their metabolites in serum samples collected from an elderly population in South China and examine the relationships between NEO exposure and OP.

Associations of neonicotinoids with insulin and glucose homeostasis parameters in US adults: NHANES 2015-2016

Neonicotinoids are replacement insecticides increasingly used for organophosphates, methylcarbamates, and pyrethroids. Experimental evidence suggests neonicotinoids may affect glucose metabolism and insulin secretion through pancreatic β cell dysfunction, oxidative stress, and inflammation. However, no epidemiologic study has investigated neonicotinoids as potential diabetogens. We examined associations between neonicotinoids with insulin and glucose homeostasis parameters among 1381 non-diabetic adults in the National Health and Nutrition Examination Survey (2015-2016). Urinary concentrations of acetamiprid, clothianidin, imidacloprid, N-desmethyl-acetamiprid, and 5-hydroxy-imidacloprid were quantified. Fasting plasma glucose, insulin, and hemoglobin A_1c (HbA_1c) were assessed. Insulin resistance was defined as a homeostatic model assessment of insulin resistance ≥2.5. We used weighted linear and logistic regression to estimate associations between detectable neonicotinoids with insulin and glucose homeostasis parameters compared to non-detectable neonicotinoid concentrations. Weighted detection frequencies for imidacloprid, 5-hydroxy-imidacloprid, and N-desmethyl-acetamiprid were 4.4 %, 21.5 %, and 32.8 %, respectively. Detectable imidacloprid (β = -4.7 μIU/mL, 95 % confidence interval [CI] -8.5, -0.8) and 5-hydroxy-imidacloprid (β = -2.4 μIU/mL, 95 % CI -4.6, -0.2) were associated with lower fasting plasma insulin levels. Individuals with detectable 5-hydroxy-imidacloprid had lower odds of insulin resistance (odds ratio [OR] = 0.3, 95 % CI 0.2, 0.7). We observed evidence of sexually dimorphic associations between N-desmethyl-acetamiprid with glucose (p_int = 0.079) and 5-hydroxy-imidacloprid with HbA_1c (p_int = 0.038), with patterns suggesting positive associations in males and negative associations in females. Associations between 5-hydroxy-imidacloprid and insulin were modified by body mass index (BMI) (p_int = 0.013). We additionally observed age modified associations between 5-hydyroxy-imidacloprid and glucose (p_int = 0.048). Results suggest neonicotinoids may be associated with insulin and glucose homeostasis indices and call for prospective studies to examine the metabolic impact of these replacement insecticides in humans.

Development of an analytical method based on solid-phase extraction and LC-MS/MS for the monitoring of current-use pesticides and their metabolites in human urine

Pyrethroids, organophosphorus pesticides and fipronil have been listed as priority chemicals in human biomonitoring studies because of their wide use and potential health effects in humans. The determination of 13 pesticides, including pyrethroids (deltamethrin, cypermethrin, permethrin, cyfluthrin, bifenthrin), organophosphorus (chlorpyrifos, chlorpyrifos-methyl, and malathion), fipronil, neonicotinoids (imidacloprid, acetamiprid and thiacloprid) and triazole (prothioconazole), together with 13 corresponding metabolites in human urine samples was achieved by solid-phase extraction and analysis by liquid chromatography coupled to tandem mass spectrometry. All targeted compounds, except malathion dicarboxylic acid, were measured with a mean within-accuracy (n = 5) of 71%-114% (RSD: 1%-14%) and between-run (n = 15) accuracy of 80%-118% (RSD: 2%-14%). Limits of quantitation of the targeted analytes ranged from 0.1 to 16 pg/mL. The detection result of urine samples from 25 volunteers indicated that the detection frequencies of 3,5,6-trichloro-2-pyridinol (median: 448 pg/mL), 6-chloropyridine-3-carboxylic acid (median: 193 pg/mL), 2-methyl-3-phenylbenzoic acid (median: 181 pg/mL), 3-phenoxybenzoic acid (median: 99 pg/mL), 2-isopropyl-6-methyl-4-pyrimidinol (median: 77 pg/mL), cyfluthrin (median: 59 pg/mL), cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (cis-DCCA, median: 53 pg/mL), trans-DCCA (median: 25 pg/mL), prothioconazole (median: 21 pg/mL), imidacloprid (median: 7 pg/mL), and prothioconazole-desthio (median: 1 pg/mL) were > 50%. The obtained results show that the validated method is suitable for the human biomonitoring of these current-use pesticides and their metabolites.

Spermiogenesis toxicity of imidacloprid in rats, possible role of CYP3A4

This study evaluated the adverse effects of low-dose imidacloprid (IMI) on the characteristics of sperm from male Wistar rats. Thirty mature male rats were equally divided into three groups and orally administered vehicle (Control Group), acceptable daily intake (ADI) concentration of IMI (Group 1), and IMI at a dose 10-fold that of the ADI (Group 2) for 90 days. The findings revealed that IMI caused abnormalities in sperm concentrations and morphologies, accompanied by an imbalance of the gonadal hormone testosterone. Histopathological damage and decrease of testosterone levels were observed in testes from rats treated with IMI. However, estradiol and gonadotropin levels were unchanged after IMI treatment. IMI inhibited the activity of cytochrome P450 3A4 (CYP3A4) and left itself existed in the organism of rats. The indicators relating to sperms and CYP3A4 activity were recovered when rats were co-treated with IMI and CYP3A4 inducer rifampicin together. These results indicated that low-dose IMI exposure caused sperm abnormalities through affecting on the spermiogenesis in testis. Inhibition of CYP3A4 activity by IMI largely contributed to its sperm toxicity. Thus, IMI exposure at doses close to real-world settings resulted in sperm toxicity on rats, which might be a potential risk factor for human reproductive diseases.

Testicular deficiency associated with exposure to cypermethrin, imidacloprid, and chlorpyrifos in adult rats

The testicular deficiency associated with exposure to three widely used insecticides in Egyptian agriculture was evaluated. Animals were orally treated with sub-lethal dose (1/50 of the oral LD₅₀) of cypermethrin (CYP), imidacloprid (IMC), and chlorpyrifos (CPF) at 5, 9 and 1.9 mg/kg/day, respectively, five times a week for one month. The CYP, IMC, and CPF exposure resulted in a significant decline in animal body weight, sperm count, motility, normality, and viability with increased head and tail deformities. Significant reduction in serum testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), testis superoxide dismutase (SOD), and reduced glutathione (GSH) levels. In contrast, catalase (CAT), lipid peroxidation (LPO), and protein carbonyl content (PCC) levels were significantly stimulated. Jointly, obtained results were confirmed by microscopic examination of testis sections. The present data concluded that the CYP, IMC, and CPF have a public health impact and violently interferes with male rat reproductive system.

Occurrence and distribution of neonicotinoids and characteristic metabolites in paired urine and indoor dust from young adults: Implications for human exposure

Neonicotinoid insecticides (NEOs) are widely used for pest control worldwide. The profile of NEOs in paired urine and indoor dust has not yet been reported in China. In this study, 40 paired samples (i.e., 160 urine and 40 indoor dust) were collected from university students and dormitories from Guangzhou City of China to measure the concentrations of six NEOs and their three metabolites. Target analytes were frequently detected in paired urine (81%-98%) and indoor dust (75%-95%) samples, with median concentrations ranging from 0.02 [specific gravity (SG) adjusted: 0.02] to 2.08 (SG-adjusted: 2.38) ng/mL in urine and from 0.05 to 2.74 ng/g in indoor dust. 5-Hydroxy-imidacloprid was predominant in urine, while N-desmethyl acetamiprid was predominant in indoor dust samples, accounting for 56% and 37%, respectively. 1-Methyl-3-(tetrahydro-3-furylmethyl) urea, a dinotefuran degradate, was measured for the first time in indoor dust, with the median level of 1.02 ng/g. Significant gender-related differences (p < 0.05) in the urinary concentrations of most NEOs were found. We calculated the estimated daily intake (EDI) of target compounds from urine and indoor measurements. The EDIs of target analytes varied among all urine and indoor dust samples, with median values ranging from 0.51 (SG-adjusted: 0.56) to 51.6 (SG-adjusted: 52.8) ng/kg bw/day and from 0.04 to 2.10 pg/kg bw/day, respectively. Moreover, the median EDIs_urine of most target analytes in females were significantly higher than (p < 0.05) those in males. The median EDIs_dust of target compounds in dust from female dormitories were slightly higher than that in dust from male dormitories. These findings indicated that females were more exposed to NEO than males. Thus, the potential health risks of exposure to NEOs and their metabolites in female adults should be addressed in future studies. To our knowledge, this study is the first to report the profiles of NEOs and their metabolites in paired urine and indoor dust samples from young adults in China.

Pesticides: formulants, distribution pathways and effects on human health - a review

Pesticides are commonly used in agriculture to enhance crop production and control pests. Therefore, pesticide residues can persist in the environment and agricultural crops. Although modern formulations are relatively safe to non-target species, numerous theoretical and experimental data demonstrate that pesticide residues can produce long-term negative effects on the health of humans and animals and stability of ecosystems. Of particular interest are molecular mechanisms that mediate the start of a cascade of adverse effects. This is a review of the latest literature data on the effects and consequences of contamination of agricultural crops by pesticide residues. In addition, we address the issue of implicit risks associated with pesticide formulations. The effects of pesticides are considered in the context of the Adverse Outcome Pathway concept.

Exposure to Organophosphate and Neonicotinoid Insecticides and Its Association with Steroid Hormones among Male Reproductive-Age Farmworkers in Northern Thailand

Several studies indicated organophosphate (OP) and neonicotinoid (NEO) insecticides are endocrine disruptors; however, data are scarce. This cross-sectional study recruited 143 male farmworkers aged 18-40 years in Fang district, Chiang Mai province, northern Thailand. OP exposure was assessed by measuring urinary dialkylphosphate (DAPs) using a gas-chromatography flame photometric detector. Urinary NEOs, their metabolites (NEO/m) and serum steroid hormones were measured using liquid chromatography-tandem mass spectrometry. Characteristics of participants were determined by face-to-face interviews. DAPs and five NEO/m were detected in more than 60% of samples. The concentration of diethylphosphate was highest among DAP metabolites (geometric mean concentration (GM: 23.9 ng/mL) and the concentration of imidacloprid (IMI) was highest among NEO/m (GM: 17.4 ng/mL). Linear regression models showed that the IMI level was positively associated with testosterone, dehydrocorticosterone (DHC) and dehydroepiandrosterone (DHEA) levels. Imidacloprid-olefin and DHEA levels were positively associated. Thiamethoxam (THX) were inversely associated with DHC and deoxycorticosterone levels. Clothianidin (CLO), THX and N-desmethyl-acetamiprid levels were positively associated with the androstenedione level. CLO and THX levels were inversely associated with the cortisone level. In conclusion, the association between NEO insecticides exposure and adrenal androgens, glucocorticoids and mineralocorticoids, suggest potential steroidogenesis activities. Our findings warrant further investigation.

Profiles of neonicotinoid insecticides and their metabolites in paired saliva and periodontal blood samples in human from South China: Association with oxidative stress markers

Neonicotinoid insecticides (NEOs) are widely used around the world. The distribution of NEOs in paired saliva and periodontal blood samples was not previously documented in China. In this study, the concentrations of six NEOs and three corresponding metabolites were measured in 188 paired saliva and periodontal blood samples collected from South China. NEOs and their metabolites were frequently detected (68-94%) in paired saliva and periodontal blood, with median levels of 0.01-0.99 ng/mL. 1-Methyl-3-(tetrahydro-3-furylmethyl) urea was the most predominant NEO in paired saliva (39%) and periodontal blood (42%). Gender-related differences in NEOs and their metabolite concentrations were found: males showed lower levels than females. We calculated the concentration ratios between saliva and periodontal blood (S/PB ratios), and found that the median S/PB ratios of NEO and their metabolites were higher than 1, indicating that NEOs and their metabolites were easily excreted via saliva. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) was measured in paired saliva and periodontal blood as a marker of oxidative stress. 8-OHdG concentrations in saliva and periodontal blood were significantly and positively correlated (p < 0.05) with the concentrations of most NEOs and their metabolites in saliva and periodontal blood samples. These findings indicated that exposure to NEOs and their metabolites is associated with oxidative stress. This study is the first to report NEOs and their metabolites in paired saliva and periodontal blood samples collected from South China.

Effects of low-level imidacloprid oral exposure on cholinesterase activity, oxidative stress responses, and primary DNA damage in the blood and brain of male Wistar rats

Imidacloprid is a neonicotinoid insecticide that acts selectively as an agonist on insect nicotinic acetylcholine receptors. It is used for crop protection worldwide, as well as for non-agricultural uses. Imidacloprid systemic accumulation in food is an important source of imidacloprid exposure. Due to the undisputable need for investigations of imidacloprid toxicity in non-target species, we evaluated the effects of a 28-day oral exposure to low doses of imidacloprid (0.06 mg/kg b. w./day, 0.8 mg/kg b. w./day and 2.25 mg/kg b. w./day) on cholinesterase activity, oxidative stress responses and primary DNA damage in the blood and brain tissue of male Wistar rats. Exposure to imidacloprid did not cause significant changes in total cholinesterase, acetylcholinesterase and butyrylcholinesterase activities in plasma and brain tissue. Reactive oxygen species levels and lipid peroxidation increased significantly in the plasma of rats treated with the lowest dose of imidacloprid. Activities of glutathione-peroxidase in plasma and brain and superoxide dismutase in erythrocytes increased significantly at the highest applied dose. High performance liquid chromatography with UV diode array detector revealed the presence of imidacloprid in the plasma of all the treated animals and in the brain of the animals treated with the two higher doses. The alkaline comet assay results showed significant peripheral blood leukocyte damage at the lowest dose of imidacloprid and dose-dependent brain cell DNA damage. Oral 28-day exposure to low doses of imidacloprid in rats resulted in detectable levels of imidacloprid in plasma and brain tissue that directly induced DNA damage, particularly in brain tissue, with slight changes in plasma oxidative stress parameters.

Occurrence of neonicotinoid insecticides and their metabolites in tooth samples collected from south China: Associations with periodontitis

Neonicotinoid insecticides (NEOs) are widely used in agricultural production processes in China and worldwide. NEOs have been an increasing concern because of their potential toxicity to nontarget organisms. However, studies that focused on human exposure to NEOs in China are limited. In this study, levels of six parent NEOs (p-NEOs), namely imidacloprid (IMI), acetamiprid (ACE), clothianidin (CLO), dinotefuran (DIN), thiamethoxam (THIX), and thiacloprid (THI), and three metabolites (m-NEOs), such as 5-hydroxy-imidacloprid (5-OH-IMI), 1-methyl-3-(tetrahydro-3-furyl methyl) urea (UF), and N-desmethyl-acetamiprid (N-dm-ACE) were measured in 127 tooth samples collected from South China. P-NEOs and m-NEOs are frequently detected (76%-93%) in tooth samples, with median levels of 0.03-1.20 ng/g. UF is the most abundant NEOs in tooth samples (36%). Females have higher NEO levels than males, and gender-related differences in NEO levels are found. Associations among most p-NEOs are also found (p < 0.05), indicating the source of human exposure to p-NEOs is related. However, no significant relationships (p > 0.05) between levels of m-NEOs and their corresponding p-NEOs are found, suggesting that exogenous m-NEOs contribute to exposure. We have also examined the associations between human NEOs exposure and periodontitis, and associations between NEO exposure and periodontitis are observed (OR = 2.63-7.33; 95% CI = 1.01-21.1, p-trend < 0.05). Our results suggest that NEO levels are associated with increased odds of prevalent periodontitis. This study is the first to report about p-NEOs and m-NEOs in tooth samples collected from South China.

A nationwide study of occurrence and exposure assessment of neonicotinoid insecticides and their metabolites in drinking water of China

Neonicotinoid insecticides (NNIs) are the most extensively used insecticides worldwide, threatening ecosystem and human health. However, nationwide studies of NNIs and their metabolites in drinking water are limited. In order to characterize the contamination status of NNIs in drinking water throughout China, we collected 884 drinking water samples including 789 tap water and 95 groundwater samples from 32 provinces (covering seven regions of mainland China: south, central, east, north, northeast, northwest, and southwest) and Hong Kong. Ten NNIs and six of their main metabolites were determined in the water samples. The relative potency factor method was used to assess the cumulative concentrations of NNIs and their metabolites (imidacloprid-equivalent total NNIs, IMI_eq) based on the chronic reference doses (cRfDs) of the NNIs or the toxic effects of the mataboilites. The IMI_eq varied among the studied regions, with a median concentration of 24.5 ng/L and a maximum concentration of 8,622 ng/L. The predominant NNIs in drinking water were acetamiprid (ACE) and imidacloprid (IMI). Compared with tap water derived from groundwater, much higher concentrations of IMI_eq and NNIs were found in tap water derived from surface water. Different concentrations and patterns of NNIs in drinking water were observed in different regions, provinces, and capital cities, mainly due to regional and provincial differences in crop types and volumes of pesticide usage. The concentrations of NNIs in the drinking water of provincial capitals and small/medium cities were higher than the concentrations in rural areas. The estimated daily intake (EDI) of IMI_eq was at least two orders of magnitude lower than the cRfD of IMI, while the NNIs in 16 drinking water samples exceeded the acceptable value (100 ng/L) recommended by the European Union. This study provided a nationwide profile of the occurrence of NNIs and their metabolites in the drinking water of China and the associated potential cumulative human health risks, taking into account of the toxicity differences between NNIs and their metabolites.

A syringe-aided apta-nanosensing method for colorimetric determination of acetamiprid

A syringe-aided apta-nanosensing method is reported for the colorimetric determination of acetamiprid. The method employs double-stranded (ds) DNA-conjugated gold nanoparticle@magnetic agarose beads, i.e., dsDNA-AuNP@MABs as peroxidase-mimicking composite probes, in which the aptamer is indirectly attached to the AuNP surface through its hybridization with complementary DNA (cDNA). Upon contact with the acetamiprid target, the probes can give perceptible color change due to the possible conformation switch from dsDNA's brush-like to cDNA's 'pancake' regime. An "air-spaced pumping" procedure using a syringe equipped with ring magnets as the operation platform was proposed to facilitate the magnetic separation of the sensing probes. Therefore, the analytical steps can be easily accomplished in a syringe, including probe loading, acetamiprid capture and magnetic separation from crude samples, chromogenic reagent loading and colorimetric visualization. Acetamiprid concentration down to 3.3 ppb can be easily identified by the naked eye. The final solution also can be transferred for quantitative measurement. Under spectrometer, the ratio of the absorbance at 652 nm in the presence and absence of acetamiprid (A/A₀) is linearly related to the acetamiprid concentration in the 0.4-4.5 ppb range. The limit of detection is calculated to be 0.24 ppb. Moreover, satisfactory recoveries ranging from 90.90 to 91.82% with relative standard deviations of ≤2.96% were obtained in analyzing real spiked samples.

Neonicotinoid insecticide and their metabolite residues in fruit juices: Implications for dietary intake in China

Neonicotinoid insecticides (NEOs) have become the most widely used insecticides worldwide, and they are ubiquitous in food (i.e., fruit juices). In the present study, occurrence of seven NEOs and four metabolites (m-NEOs) in 400 fruit juice samples were investigated. NEOs and m-NEOs were frequently detected (65%-86%) in fruit juice samples. The median residues of NEOs and m-NEOs were ranged from 0.06 ng/mL to 0.94 ng/mL. Seasonal variations in NEOs and m-NEOs in fruit juices were found, indicating that the target analyte residues during the dry season were remarkably higher than those of residues during wet season. The relative potency factor (RPF) method was used to integrate individual NEOs into a single metric [imidacloprid (IMI_RPF)] representing the intakes of IMI equivalent to total NEOs for each fruit juice sample. The estimated daily intake (EDI) of total NEOs for the general Chinese population was obtained. The median IMI_RPF for total fruit juices was 13.4 ng/g, and the median EDI of NEOs was 18.2 ng/kg bw/day for the general population. Although the EDIs in this study were considerably lower than the acceptable daily intake (60 μg/kg bw/day, ADI), the dietary exposure risks for total NEOs should not be ignored because of the increasing usage of NEOs and their ubiquitous presence in fruit juices in China. To the best of our knowledge, this report was the first time to document residues of NEO and m-NEO in fruit juice samples collected from China.

Neonicotinoid-containing insecticide disruption of growth, locomotion, and fertility in Caenorhabditis elegans

Neonicotinoids, a class of insecticides structurally similar to nicotine that target biting and sucking insects, are the most widely used insecticides today, in part due to their supposed low toxicity in other organisms. However, a growing body of research has found that even low doses of neonicotinoids can induce unexpected negative effects on the physiology and survival of a wide range of non-target organisms. Importantly, no work has been done on the commercial formulations of pesticides that include imidacloprid as the active ingredient, but that also contain many other components. The present study examines the sublethal effects of "Tree and Shrub"™ ("T+S"), a commercial insecticide containing the neonicotinoid imidacloprid as its active ingredient, on Caenorhabditis elegans. We discovered that "T+S" significantly stunted the overall growth in wildtype nematodes, an effect that was exacerbated by concurrent exposure to heat stress. "T+S" also negatively impacted fecundity as measured by increased germline apoptosis, a decrease in egg-laying, and fewer viable offspring. Lastly, exposure to "T+S" resulted in degenerative changes in nicotinic cholinergic neurons in wildtype nematodes. As a whole, these findings demonstrate widespread toxic effects of neonicotinoids to critical functions in nematodes.

Evaluating imidacloprid exposure among grape field male workers using biological and environmental assessment tools: An exploratory study

Imidacloprid is a neonicotinoid insecticide commonly injected through agricultural drip irrigation systems to reduce the population of vine mealybugs (P. ficus) in grape farms. There is a growing concern of potential human health effects of imidacloprid, however, there is limited information on the exposure to imidacloprid in farm workers. Imidacloprid exposure was evaluated in this exploratory study of 20 male migrant grape workers sampled five days after imidacloprid was injected in the irrigation system during winter and summer seasons. We administered a questionnaire on work activities, exposure characteristics, and socio-demographics and collected personal air, hand wipe, and spot urine samples. Heat exposure was also assessed. Spearman's correlation coefficients and Wilcoxon rank-sum tests were utilized to evaluate associations and differences in imidacloprid exposures with socio-demographic, occupational, and environmental characteristics. All participants had less than a high school education and about half identified an Indigenous language as their primary language. Although not detected in air samples, imidacloprid was detected in 85% of the hand wipes (median: 0.26: 0.41 μg/wipe, range: 0.05-7.10 μg/wipe). The majority of participants (75%) had detectable urinary concentrations of imidacloprid (median: 0.11 μg/g creatinine, range: 0.05-3.90 μg/g of creatinine), and nearly all (95%) had detectable urinary concentrations of 5-hydroxy-Imidacloprid (5-OH-IMI), a metabolite of imidacloprid (median: 1.28 μg/g creatinine, range: 0.20-27.89 μg/g creatinine). There was a significant correlation (p < 0.001) between imidacloprid in hand wipes and urinary imidacloprid and 5-OH-IMI (rs: 0.67 for imidacloprid and 0.80 for 5-OH-IMI). Hand temperature was significantly and positively correlated (p < 0.05) with imidacloprid concentration on hand wipes (rs: 0.70), and urinary biomarkers (rs: 0.68 for imidacloprid, and 0.60 for 5-OH-IMI) suggesting that working in high temperatures may influence the exposure and absorption of imidacloprid. Thus, research on farm workers would benefit in the future by evaluating imidacloprid exposure in relation to heat stress and other occupational factors.

Urinary Metabolites of Neonicotinoid Insecticides: Levels and Recommendations for Future Biomonitoring Studies in China

Neonicotinoids (NEOs) are insecticides that are widely used around the world. Following exposure, NEOs get metabolized in human bodies. The biomarkers to assess human NEO exposure are not well described because of the lack of information on the metabolites of NEOs (m-NEOs). In this study, five m-NEOs including N-desmethyl-acetamiprid (N-dm-ACE), 5-hydroxy-imidacloprid (5-OH-IMI), olefin-imidacloprid (Of-IMI), 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine (DIN-G), and 1-methyl-3-(tetrahydro-3-furylmethyl) (DIN-U) were measured in 275 urine samples collected from 10 cities in China. All of the m-NEOs were frequently detected in urine samples with the median concentrations ranging from 0.42 (DIN-G) to 1.02 (5-OH-IMI) ng/mL. The urinary concentrations of N-dm-ACE and 5-OH-IMI measured in China were higher than those reported from Japan and the USA. In comparison to the parent NEO (i.e., acetamiprid, ACE; imidacloprid, IMI; and dinotefuran, DIN) concentrations reported in the same set of samples by our research group, the median ratios of m-NEO to the corresponding parent NEO (m-NEO/NEO) ranged from 4.95 (DIN-G/DIN) to 37.7 (N-dm-ACE/ACE), indicating that NEOs are mainly present as metabolites rather than the parent forms. Furthermore, the ratio of Σm-NEOs/ΣNEOs was significantly (p < 0.01) higher in females than in males, suggesting that NEOs are more readily metabolized in females or females are more highly exposed to m-NEOs. To our knowledge, this is the first study to measure Of-IMI, DIN-G, and DIN-U levels in urine samples from China. We recommend biomonitoring studies to include N-dm-ACE, 5-OH-IMI, and DIN-U (and DIN-G) for clear understanding of human exposure to ACE, IMI, and DIN, respectively.

A critical review on the potential impacts of neonicotinoid insecticide use: current knowledge of environmental fate, toxicity, and implications for human health

Neonicotinoid insecticides are widely used in both urban and agricultural settings around the world. Historically, neonicotinoid insecticides have been viewed as ideal replacements for more toxic compounds, like organophosphates, due in part to their perceived limited potential to affect the environment and human health. This critical review investigates the environmental fate and toxicity of neonicotinoids and their metabolites and the potential risks associated with exposure. Neonicotinoids are found to be ubiquitous in the environment, drinking water, and food, with low-level exposure commonly documented below acceptable daily intake standards. Available toxicological data from animal studies indicate possible genotoxicity, cytotoxicity, impaired immune function, and reduced growth and reproductive success at low concentrations, while limited data from ecological or cross-sectional epidemiological studies have identified acute and chronic health effects ranging from acute respiratory, cardiovascular, and neurological symptoms to oxidative genetic damage and birth defects. Due to the heavy use of neonicotinoids and potential for cumulative chronic exposure, these insecticides represent novel risks and necessitate further study to fully understand their risks to humans.

Zero-Order Catalysis in TAML-Catalyzed Oxidation of Imidacloprid, a Neonicotinoid Pesticide

Bis-sulfonamide bis-amide TAML activator [Fe{4-NO₂ C₆ H₃ -1,2-(NCOCMe₂ NSO₂ )₂ CHMe}]^- (2) catalyzes oxidative degradation of the oxidation-resistant neonicotinoid insecticide, imidacloprid (IMI), by H₂ O₂ at pH 7 and 25 °C, whereas the tetrakis-amide TAML [Fe{4-NO₂ C₆ H₃ -1,2-(NCOCMe₂ NCO)₂ CF₂ }]^- (1), previously regarded as the most catalytically active TAML, is inactive under the same conditions. At ultra-low concentrations of both imidacloprid and 2, 62 % of the insecticide was oxidized in 2 h, at which time the catalyst is inactivated; oxidation resumes on addition of a succeeding aliquot of 2. Acetate and oxamate were detected by ion chromatography, suggesting deep oxidation of imidacloprid. Explored at concentrations [2]≥[IMI], the reaction kinetics revealed unusually low kinetic order in 2 (0.164±0.006), which is observed alongside the first order in imidacloprid and an ascending hyperbolic dependence in [H₂ O₂ ]. Actual independence of the reaction rate on the catalyst concentration is accounted for in terms of a reversible noncovalent binding between a substrate and a catalyst, which usually results in substrate inhibition when [catalyst]≪[substrate] but explains the zero order in the catalyst when [2]>[IMI]. A plausible mechanism of the TAML-catalyzed oxidations of imidacloprid is briefly discussed. Similar zero-order catalysis is presented for the oxidation of 3-methyl-4-nitrophenol by H₂ O₂ , catalyzed by the TAML analogue of 1 without a NO₂ -group in the aromatic ring.

Imidacloprid disrupts the endocrine system by interacting with androgen receptor in male mice

In the current study, six-week-old male ICR mice were administered imidacloprid (IMI) at concentrations of 3, 10 and 30 mg/L for a duration of 10 weeks to investigate the toxicity of IMI on the endocrine system. We observed that testicular morphology was severely impaired and damaged, and the levels of serum testosterone (T) and the expression of androgen receptor (AR) decreased significantly. Molecular docking analysis suggested that IMI docks into the active site of AR successfully and that three key hydrogen bonds were formed with the active site residues Glu11, Gln41 and Lys138. The binding free energy value of the AR-IMI complex suggested a stable binding between IMI and AR. All these results indicated that IMI could interact with AR. In addition, major genes in the testis involved in the synthesis of cholesterol and T were generally inhibited, and the serum cholesterol sources were also reduced. Moreover, the aromatase in male mice was lacking after subchronic IMI exposure. The data acquired from the present study indicated that IMI could lead to endocrine disruption by interacting with AR and influence the expression of genes involved in the production of T in male mice.

An environmentally realistic pesticide and copper mixture impacts embryonic development and DNA integrity of the Pacific oyster, Crassostrea gigas

Frequent occurrences of pesticides in the environment have raised concerns that combined exposure to these chemicals may result in enhanced toxicity through additive or synergistic interaction between compounds. Spermatozoa and embryos of the Pacific oyster, Crassostrea gigas, were exposed to different concentrations of a pesticide mixture with and without copper, mimicking the cocktail of pollutants occurring in the oyster culture area of Arcachon Bay. For the 1× exposure condition, measured concentration corresponds to a total concentration of 1.083 μg L^-1 for the mixture of 14 pesticides and to 6.330 μg L^-1 for copper (Cu). Several endpoints including larval abnormalities, DNA damage to spermatozoa and embryo and gene expression in D-larvae were investigated. Results demonstrated that pesticide mixtures in combination with or without copper induced a dose-dependent increase in embryotoxic and genotoxic effects on D-larvae from the lowest tested dose of 0.1×. Transcription of genes involved in anti-oxidative stress (cat), respiratory chain (coxI), metal detoxification (mt1 and mt2), and cell cycle arrest and apoptosis (p53) was found to be significantly downregulated while the xenobiotic biotransformation gene gst was significantly upregulated in embryos exposed to pesticide mixture with and without Cu. These findings raise the question of the possible impacts of mixtures of pesticides and metals on wild or farmed oyster populations from polluted coastal marine areas.

Adverse reproductive effects of S100A9 on bovine sperm and early embryonic development in vitro

The phenomenon of aging arises from multiple, complex interactions causing dysfunction in cells and organs. In particular, fertility drastically decreases with age. Previously, we have demonstrated that the functional characteristics of the bovine oviduct and uterus change with the age-dependent upregulation of inflammation and noted that S100A9 triggers inflammatory responses in oviduct epithelial cells. In the present study, we investigated the hypothesis that S100A9 affects reproductive events to aspect such as sperm function, fertilization, and the development of the embryo in cows. To investigate the effect of S100A9 on bovine sperm, we incubated sperms in vitro with S100A9 for 5 h and observed significantly decreased sperm motility and viability. During in vitro fertilization, S100A9 treatment for 5 h did not affect the rate of fertilization, time of first division of embryos, or embryo development to blastocyst stage. Treatment of 2-cell stage embryos with S100A9 for 5 h significantly reduced the proportion of cells undergoing normal division (4-8 cell embryos) and embryo development to the blastocyst stage. In experiment involving 24 h treatment of 2-cell embryos, the development of all embryos stopped at the 2-cell stage in the S100A9-treated group. In blastocyst-stage embryos, S100A9 treatment significantly stimulated the expression of endoplasmic reticulum (ER) and the mRNA expression of ER stress markers, and activated caspase-3 with subsequent nuclear fragmentation. Pre-treatment with an ER stress inhibitor significantly suppressed caspase-3 activation by the S100A9 treatment, suggesting that S100A9 induces blastocyst dysfunction by apoptosis (via caspase-3 activation) depending on ER stress. These results indicate that direct exposure to S100A9 exerted adverse effects on sperm function and embryo development. These findings suggest that excessive dose of S100A9 may have an adverse effect to the reproductive machinery by inducing inflammation and tissue dysfunction.

Characteristics of neonicotinoid imidacloprid in urine following exposure of humans to orchards in China

Imidacloprid (IMI) is a typical neonicotinoid with the largest usage in agricultural orchards in China. The long-term repeated use and the lack of proper protective measures may result in rural farmers and people living near orchards to be inevitably exposed to IMI. Excessive exposure may cause potential adverse effects on human health. To explore the characteristics of human exposure to IMI in urine, different groups of people, including pesticide applicators and their family members, and kindergarten children near IMI-applied orchards were investigated. The IMI and metabolite, 6-chloronicotinic acid (6-CNA), concentrations in urine were creatinine-adjusted to compensate for a possible dilution effect. Target analytes were detected in 100% of 1926 urine samples. The results showed that the IMI concentration in the 1-d urine from the rural residents significantly increased after a spraying event (p < 0.05) and reached the highest concentration (Geomean: 16.42 μg/g creatinine for IMI; 7.33 μg/g creatinine for 6-CNA) in the 2-d urine samples. The pesticide applicators of different genders had almost the same exposure environment (IMI Geomean of 13.25 μg/g creatinine for males and 14.71 μg/g creatinine for females) (p > 0.05). Females had higher exposure concentrations than that of males. People from different villages demonstrated diverse exposure levels with Geomean differences of 1.13-3.28 fold. For 3-6 years-old children, urinary concentrations from the rural group (Geomean: 3.73 μg/g creatinine for IMI; 3.95 μg/g creatinine for 6-CNA) were significantly higher than that of the urban group (Geomean: 1.13 μg/g creatinine for IMI; 0.88 μg/g creatinine for 6-CNA) (p = 0.00001), and the younger children tended to have higher exposure risk. Our findings showed that people in the Henan orchard areas were likely exposed to IMI to varying degrees. Further research on the health risk evaluation of IMI and controlling the exposure risks is needed.

A nationwide survey of urinary concentrations of neonicotinoid insecticides in China

Neonicotinoid insecticides (NEOs) are emerging pesticides of concern due to their potential toxicity to non-target species (e.g., bees, fish and birds). China is an important producer and user of NEOs in the world. Studies on human exposure to NEOs in China are very limited. In this study, urinary levels of six NEOs, namely acetamiprid (ACE), clothianidin (CLO), dinotefuran (DIN), imidacloprid (IMI), thiacloprid (THD), and thiamethoxam (THM) were determined in 324 individuals from 13 cities in China. Across all sampling locations, total NEO concentrations (ΣNEOs; sum of six NEOs) were dominated by CLO (median: 0.24 ng/mL), IMI (0.21 ng/mL), THM (0.15 ng/mL) and DIN (0.14 ng/mL) collectively accounting for 98% of the concentrations. Urinary concentrations of each NEO varied depending on the sampling location with the median values ranged from 0.057 to 1.2 ng/mL for CLO, from 0.036 to 0.83 ng/mL for DIN, from 0.069 to 3.2 ng/mL for IMI, and from 0.062 to 0.45 ng/mL for THM. Sex-related differences in IMI, ACE and ΣNEOs concentrations were observed with males presenting significantly higher urinary levels than did females. All six NEOs were significantly positively correlated (r = 0.135 to 0.661, p < 0.05) with each other, suggesting that the exposure sources of NEOs are common or related. On the basis of urinary IMI levels, we calculated the median daily intake (DI; mean and range) of IMI to be 1.6 (4.1, <0.02-55) μg/day, or 0.034 (0.11, <0.0003-2.1) μg/kg bw/day. To our knowledge, this is the first study to document the ubiquitous occurrence of and human exposure to NEOs in China.

A sublethal dose of the neonicotinoid insecticide acetamiprid reduces sperm density in a songbird

Farmland bird species are particularly exposed to pesticides through various pathways. Among pesticides, neonicotinoids insecticides are commonly used in agriculture, but their influence on bird reproductive capacities is poorly understood. In this study, we experimentally tested the effects of the neonicotinoid acetamiprid on House sparrows' sperm quality and oxidative status following ingestion of a low and field-realistic dose of the compound. To do so, 56 males were captured, held and orally dosed seven times over 19 days of experiment with either a saline solution (control) or an acetamiprid-saline solution, and sperm samples were retrieved before and after the experiment. The overall dose given to the birds corresponded to 0.5% of the LD₅₀ for the Zebra finch (5.7 mg/kg BW) spread into 7 separate doses and administered every three days over the entire duration of the study (ca. 0.07% LD₅₀ per oral dose). Sperm mobility and sperm oxidative status were unaffected by the treatment, but sperm density was. Birds that received oral doses of acetamiprid suffered a significant decline in their sperm density compared to control birds. This result was confirmed by a significant decrease in the activity of the antioxidant enzyme SOD in the sperm of acetamiprid-dosed birds. These results provide the first evidence of sublethal toxicity of acetamiprid in a songbird and suggest that passerine birds' fertility may be negatively affected by very small doses of neonicotinoids in the wild.

Investigating the potential protective effects of natural product quercetin against imidacloprid-induced biochemical toxicity and DNA damage in adults rats

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Imidacloprid insecticide causes hepatotoxicity, renal damage and DNA damage.

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Quercetin revealed a significant protective action against the toxic effects of Imidacloprid.

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Quercetin counteracts the imidacloprid effects on liver, Kidney and DNA damage to the normal level.

Quercetin (QT) is a natural antioxidant materials that’s possesses different type of pharmacological activities. In the current study, the protective effect QT against imidacloprid (IMD)-induced toxicity in rats was studied. The experiment included thirty-six adult male rats groups treated with QT, IMD (two different doses), their combinations and control non-treated group for 21 consecutive days. Different biochemical analysis (serum liver and kidney enzymes level, cholesterol and Glucose levels) were evaluated. DNA damage using comet assay and histopathological examination of different body organs were also screened. Treatment with IMD increased ALT, AST, serum urea, creatinine, cholesterol and Glucose levels but decreased the levels of serum total protein, albumin and body weight with induction in triacylglycerol and cholesterol levels. Animals treated with QT prior to IMD administration showed normal enzymatic levels which indicating a protective effect of QT. In addition, QT protected the different body organs from the histological changes and DNA damages induced by IMD toxicity. The present results showed the protective effect of QT as a natural material against the IMD induced toxicity at different doses.

Calibration of sperm concentration for in vitro fertilization in a mouse reprotoxicity model

Xenobiotics, such as chemicals and pesticides, may result in adverse effects on reproduction in human and animals. Using in-vitro embryo production as a testing system reveals details of fertilization (IVF) and early embryonic development (IVC). The aim of our study was to perform a systematical calibration of sperm concentration in an IVF/IVC system, using an outbred mouse strain, and further determine the sperm concentration that furnishes a sensitive assessment of sperm fertilizing capacity in relation to reprotoxic evaluations. By performing breakpoint analysis, the results revealed a maximum two-cell percentage (51%, 95% CI: 38 to 69%) at 3.6 × 10⁴ sperm/ml (95% CI: 2.1 × 10⁴ to 6.1 × 10⁴). For future application of the IVF/IVC system, a sperm concentration lower than this breakpoint concentration is required to be within the responsive range for determining sperm fertilizing capacity. We conclude that a relatively low sperm concentration (2.5 × 10⁴ sperm/ml) is a precondition in a mouse IVF/IVC system in order to detect potential reprotoxic effects on sperm fertilizing capacity. Our study illustrates that a systematic approach is necessary for validation and appropriate use of such in-vitro system used for reproductive toxicity testing.