Toxicological impact of technical imidacloprid on ovarian morphology, hormones and antioxidant enzymes in female rats

Comparison of prenatal and postnatal exposure to neonicotinoids and their temporal trends in breast milk

Although the potential effects of neonicotinoids (NEOs) in early life have received considerable attention, data on the exposure of mothers and infants to NEOs are scarce. In this study, four parent NEOs and one metabolite were widely detected in paired maternal serum (MS), umbilical cord serum (UCS) and breast milk (BM) samples, with median total NEO concentrations (ΣNEOs) of 113, 160 and 69 ng/L, respectively. Decreasing trends were observed for N-desmethyl-acetamiprid (30 %/year), acetamiprid (22 %/year) and ΣNEOs (15 %/year) in breast milk between 2014 and 2022, whereas increasing trends were seen for clothianidin (17 %/year) and thiamethoxam (30 %/year). N-desmethyl-acetamiprid was the predominant compound in all matrices. However, the contributions of N-desmethyl-acetamiprid (35 %) and thiamethoxam (36 %) in breast milk were similar in 2022. Moreover, thiamethoxam has become the predominant contributor to the estimated daily intake of ΣNEOs since 2018, with the highest contribution of 71 % in 2022, suggesting the effects of NEOs continue to evolve and more attention should be paid to the new NEOs. Notably, the correlations and ratios of NEOs between paired UCS and MS were more significant and higher than those between paired BM and MS, respectively, indicating that NEO exposure was largely affected by the prenatal period.

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.

Structural gonadal lesions observed in Japanese quail (Coturnix coturnix japonica) following exposure during puberty to the neonicotinoid pesticide, imidacloprid

Exposure to the neonicotinoid insecticide, imidacloprid (IMI), causes reproductive toxicity in mammals and reptiles. However, reports on the effects of IMI on the gonads in birds are grossly lacking. Therefore, this study investigated the effects of pubertal exposure to IMI on the histology, ultrastructure, as well as the cytoskeletal proteins, desmin, smooth muscle actin and vimentin, of the gonads of Japanese quail (Coturnix coturnix japonica). Quails were randomly divided into four groups at 5 weeks of age. The control group was given only distilled water, whereas, the other three experimental groups, IMI was administered by oral gavage at 1.55, 3.1, and 6.2 mg/kg, twice per week for 4 weeks. Exposure to IMI doses of 3.1 and 6.2 mg/kg caused dose-dependent histopathological changes in the ovary and testis. In the ovary, accumulation of lymphocytes, degenerative changes, and necrosis with granulocyte infiltrations were observed, while in the testis, distorted seminiferous tubules, germ cell sloughing, vacuolisations, apoptotic bodies, autophagosomes, and mitochondrial damage were detected. These changes were accompanied by a decreased number of primary follicles (P ≤ 0.05) in the ovary and a decrease (P ≤ 0.05) in the epithelial height, luminal, and tubular diameters of seminiferous tubules at the two higher dosages. In addition, IMI had a negative effect on the immunostaining intensity of desmin, smooth muscle actin, and vimentin in the ovarian and testicular tissue. In conclusion, exposure to IMI during puberty can lead to a range of histopathological alterations in the gonads of Japanese quails, which may ultimately result in infertility.

Neonicotinoid Pesticides Affect Developing Neurons in Experimental Mouse Models and in Human Induced Pluripotent Stem Cell (iPSC)-Derived Neural Cultures and Organoids

Neonicotinoids are synthetic, nicotine-derived insecticides used worldwide to protect crops and domestic animals from pest insects. The reported evidence shows that they are also able to interact with mammalian nicotine receptors (nAChRs), triggering detrimental responses in cultured neurons. Exposure to high neonicotinoid levels during the fetal period induces neurotoxicity in animal models. Considering the persistent exposure to these insecticides and the key role of nAChRs in brain development, their potential neurotoxicity on mammal central nervous system (CNS) needs further investigations. We studied here the neurodevelopmental effects of different generations of neonicotinoids on CNS cells in mouse fetal brain and primary cultures and in neuronal cells and organoids obtained from human induced pluripotent stem cells (iPSC). Neonicotinoids significantly affect neuron viability, with imidacloprid (IMI) inducing relevant alterations in synaptic protein expression, neurofilament structures, and microglia activation in vitro, and in the brain of prenatally exposed mouse fetuses. IMI induces neurotoxic effects also on developing human iPSC-derived neurons and cortical organoids. Collectively, the current findings show that neonicotinoids might induce impairment during neuro/immune-development in mouse and human CNS cells and provide new insights in the characterization of risk for the exposure to this class of pesticides.

Endocrine-disrupting effects of bisphenol-A, thiamethoxam, and fipronil in hormone-naïve transmen compared to cis-women

BACKGROUND

Current evidence suggests that the etiology of gender dysphoria (GD) is multifactorial: this, however, remains unclear. Endocrine-disrupting chemicals (EDCs) are one of the etiological hypotheses.

OBJECTIVES

In this study, we aimed to evaluate the urinary levels of bisphenol A (BPA), thiamethoxam, and fipronil in hormone-naïve transmen compared with case-matched cis-women as well as the relation between sex hormone levels and EDCs.

METHODS

Drug-naïve transmen diagnosed with GD and who were referred from the psychiatry outpatient clinic to the outpatient clinic of the Department of Endocrinology, Marmara University Hospital, were included in the study. These individuals were assessed for eligibility; 38 drug-naïve transmen and 22 cis-women were recruited as the control group. After anthropometric evaluation laboratory tests for FSH, LH, total testosterone, and estradiol were carried out, spot urine samples were collected to evaluate the urine metabolic excretion of BPA, thiamethoxam, and fipronil.

RESULTS

We found that androgens, total testosterone, androstenedione, and DHEAS levels were significantly higher in transmen than in cis-women. Thiamethoxam was considerably higher in cis-women than in transmen, whereas fipronil and BPA levels were similar in both groups. A negative correlation was found between thiamethoxam and testosterone and between thiamethoxam and BPA levels.

CONCLUSION

The available data suggest that the EDCs that we are most exposed to in our lives are not the only factor in GD development. Even transmen who have not taken hormone replacement have high testosterone levels; however, the mechanism has not as yet been elucidated. The challenge is to determine whether this is a factor leading to GD or a condition that develops in common with GD.

Was the massive increase in use of teratogenic agrichemicals in western states (USA) associated with declines in wild ruminant populations between 1994 and 2013?

Population declines were documented in multiple ruminant species in Montana and surrounding states starting in 1995. While weather, food sources, and predation certainly contributed, the declines were often attributed, at least partly, to unexplained factors. Use of teratogenic agrichemicals, notably neonicotinoid insecticides, fungicides, and glyphosate-based herbicides, massively increased regionally in 1994-96. The question explored in this review is whether this vastly increased use of these teratogenic pesticides might have contributed to observed population declines. We provide references and data documenting that specific developmental malformations on vertebrates can be associated with exposure to one or more of these agrichemicals. These pesticides are known to disrupt thyroid and other hormonal functions, mitochondrial functions, and biomineralization, all of which are particularly harmful to developing fetuses. Exposures can manifest as impaired embryonic development of craniofacial features, internal and reproductive organs, and musculoskeletal/integumental systems, often resulting in reproductive failure or weakened neonates. This paper reviews: a) studies of ruminant populations in the region, especially elk and white-tailed deer, prior to and after 1994; b) published and new data on underdeveloped facial bones in regional ruminants; c) published and new data on reproductive abnormalities in live and necropsied animals before and after 1994; and d) studies documenting the effects of exposures to three of the most applied teratogenic chemicals. While answers to the question posed above are complex and insufficient evidence is available for definitive answers, this review provides ideas for further consideration.

Resveratrol alleviates imidacloprid-induced mitochondrial apoptosis, necroptosis, and immune dysfunction in chicken lymphocyte lines by inhibiting the ROS/MAPK signaling pathway

Imidacloprid (IMI) is a neonicotinoid insecticide with the highest global market share, and IMI exposure in the environment can negatively affect many nontarget organisms (a general term for organisms affected by drugs other than target organisms). Resveratrol (RSV), a non-flavonoid polyphenolic organic compound derived from peanuts, grapes, and other plants, has anti-inflammatory and antioxidant effects. It is currently unclear how RSV protects against cell damage caused by IMI. Therefore, we established an experimental model of chicken lymphocyte lines exposed to 110 μg/mL IMI and/or 0.5 μM RSV for 24 h. According to the experimental results, IMI markedly raised intracellular reactive oxygen species levels and diminished the activity of the cellular antioxidant enzymes (CAT, SOD, and GPx), leading to MDA accumulation and decreased T-AOC. JNK, ERK, and P38, the essential components of the mitogen-activated protein kinase (MAPK) signaling pathway, were also expressed more when IMI was present. Additionally, IMI resulted in upregulation of mitochondrial apoptosis (Caspase 3, Caspase 9, Bax, and Cyt-c) and necroptosis (Caspase 8, RIPK1, RIPK3, and MLKL) related factors expression, downregulation of Bcl-2 expression, induction of upregulation of cytokine IL-6 and TNF-α expression, and downregulation of IFN-γ expression. The combined treatment of RSV and IMI significantly reduced cellular oxidative stress levels, inhibited the MAPK signaling pathway, and alleviated IMI-induced mitochondrial apoptosis, necroptosis, and immune dysfunction. To summarize, RSV antagonized IMI-induced mitochondrial apoptosis, necroptosis, and immune dysfunction in chicken lymphocyte lines by inhibiting the ROS/MAPK signaling pathway.

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.

Effects of exposure to the neonicotinoid pesticide clothianidin on mouse intestinal microbiota under unpredictable environmental stress

Recent research has demonstrated the toxicity of neonicotinoid pesticides (NNs) in mammals through their interaction with nicotinic acetylcholine receptors (nAChRs). These effects are reported to extend to the intestinal microbiota as well. In addition, environmental stress affects the expression of nAChRs, which may alter sensitivity to NNs. In this study, we analyzed the intestinal microbiota of mice exposed to clothianidin (CLO), a type of NN, under environmental stress, and aimed to clarify the effects of such combined exposure on the intestinal microbiota. C57BL/6N male mice (9 weeks old) were subchronically administered a no-observed-adverse-effect-level (NOAEL) CLO-mixed rehydration gel for 29 days and simultaneously subjected to chronic unpredictable mild stress (CUMS). After the administration period, cecum contents were collected and analyzed by 16S rRNA sequencing for intestinal microbiota. CLO exposure alone resulted in alterations in the relative abundance of Alistipes and ASF356, which produce short-chain fatty acids. The addition of CUMS amplified these changes. On the other hand, CLO alone did not affect the relative abundance of Lactobacillus, but the abundance decreased when CUMS was added. This study revealed that the combined exposure to CLO and stress not only amplifies their individual effects on intestinal microbiota but also demonstrates combined and multifaceted toxicities.

Health risks of neonicotinoids chronic exposure and its association with glucose metabolism: A case-control study in rural China

Since neonicotinoids (NNIs) are widely used around the world, they are extensively distributed in the environment and frequently occurred in humans. This study was conducted to assess the risk of NNIs residues in vegetables and fruits in Henan province, and evaluate the associations of NNIs single and mixed exposure with glucose metabolism, and further explore whether testosterone mediated these relationships in Henan rural population. The data of vegetables and fruits were collected from Henan Province in 2020-2021, and participants were drawn from the Henan Rural Cohort study. Hazard quotient (HQ) and hazard index (HI) were used to assess the risk of exposure to the individual and combined NNIs through vegetables or fruits intake. Relative potency factor (RPF) method was utilized to normalize each NNIs to imidacloprid (IMIRPF). Generalized linear models were used to explore the effects of each NNIs and IMIRPF on glucose metabolism. Weight quartile sum (WQS) regression and Bayesian kernel machine regression (BKMR) model were applied to estimate the effect of NNIs mixtures on glucose metabolism. Mediation analysis was employed to explore whether testosterone mediated these relationships. The HQs and HI in both vegetables and fruits were much lower than 1, which indicated that NNIs in vegetables and fruits were not expected to cause significant adverse effects. However, plasma natural logarithm nitenpyram (Ln_NIT), Ln_thiacloprid-amid (Ln_THD-A), and Ln_IMIeq were positively associated with type 2 diabetes mellitus (T2DM) (odds ratio (OR) (95% confidence interval (CI)): 1.12 (1.05, 1.19), 1.21 (1.10, 1.32), and 1.48 (1.22, 1.80)). Both WQS regression and BKMR models observed significantly positive associations between NNIs mixture exposure and T2DM. Testosterone partially mediated these associations among women (PE = 6.67%). These findings suggest that human NNIs exposure may impair glucose metabolism and could contribute to rising rates of T2DM, and it's necessary to regulate the use of pesticides in rural areas.

Cytotoxic effects of dose dependent inorganic magnesium oxide nanoparticles on the reproductive organs of rats

INTRODUCTION

Magnesium oxide nanoparticles (MgO NPs) have a variety of applications that have contributed to their elevated popularity, however, the safety and toxic effects on humans are also of concern with these increased applications. There is insufficient data regarding the effect of MgO NPs on reproductive organs, which are crucial aspects to the body's vital physiological functions. The present study was undertaken in male and female rats to assess the reproductive toxicological potential of two doses (low versus high) of MgO NPs on testicular and ovarian tissues. The toxicity was evaluated using histological, hormonal, and oxidative parameters.

MATERIAL AND METHODS

In this work, magnesium oxide nanoparticles (MgO NPs) were synthesized by the sol-gel route and were characterized by X ray diffraction analysis (XRD) and Fourier transform infra-red spectroscopy (FTIR). Forty-eight adult Wister albino rats were used in this experiment which were divided into groups of male and female, and then further into control, low dose MgO NPs, and high dose MgO NPs. The low dose used was 131.5 mg/kg b.w. (1/10 LD50) while the high dose used was 263 mg/kg b.w. (1/5 LD50). All doses were given orally by gastric tube. After 4 weeks, blood samples were collected to investigate the level of sex hormones and both ovarian and testicular tissues were examined for variable oxidative parameters and histopathological changes by light microscopy.

RESULTS

The obtained findings showed that high dose of MgO NPs produced considerable changes in sex hormones and stress parameters in both male and female rats in comparison to the low dose and control groups. Histomorphometric analysis demonstrated the presence of histopathological alterations in the testicular and ovarian tissues.

CONCLUSION

The results of this study showed dose-dependent adverse effects of MgO NPs on the testis and ovary both functionally and histopathologically as compared to the control rats.

Reproductive effects of pubertal exposure to neonicotinoid thiacloprid in immature male mice

Thiacloprid (THIA) is a kind of neonicotinoid, a widely used insecticide class. Animal studies of adult and prenatal exposure to THIA have revealed deleterious effects on mammalian sperm fertility and embryonic development. A recent cross-sectional study linked higher THIA concentrations to delayed genitalia development stages in adolescent boys, suggesting that pubertal exposure to THIA may adversely affect reproductive development in immature males. Hence, this study aimed to investigate the effects of daily oral administration of THIA during puberty on the reproductive system of developing male mice. Young male C57 BL/6 J mice aged 21 days were administrated with THIA at concentrations of 10 (THIA-10), 50 (THIA-50) and 100 mg/kg (THIA-100) for 4 weeks by oral gavage. It is found that exposure to 100 mg/kg THIA diminished sexual behavior in immature male mice, caused a decrease in the spermatogenic cell layers and irregular arrangement of the seminiferous epithelium, and down-regulated the mRNA levels of spermatogenesis-related genes Ddx4, Scp3, Atg5, Crem, and Ki67, leading to an increase of sperm abnormality rate. In addition, THIA exposure at 50 and 100 mg/kg reduced the serum levels of testosterone and FSH, and decreased the expression levels of Star and Cyp11a1 related to testosterone biosynthesis. THIA exposure at 10 mg/kg did not produce any of the above significant changes. In conclusion, the high dose of THIA exposure impaired reproductive function in immature mice. It seems that THIA has no detrimental effects on the reproductive system of mice at low dose of 10 mg/kg.

Melatonin Supplementation during In Vitro Maturation of Porcine Oocytes Alleviates Oxidative Stress and Endoplasmic Reticulum Stress Induced by Imidacloprid Exposure

Imidacloprid (IMI) is an endogenous neonicotinoid insecticide widely used in agriculture and has attracted researchers' attention because of its risks to the environment and human health. Melatonin (MT) is an antioxidant hormone produced by the pineal gland of the brain. Studies have shown that it has a variety of physiological functions and plays a crucial role in the development of animal germ cells and embryos. The potential protective effects of MT against oocyte damage caused by neonicotinoid pesticide toxicity remain unclear. In this study, we report the toxicity of IMI against, and its effects on the quality of, porcine oocytes and the protective effect of MT on IMI-exposed oocytes. The results show that IMI exposure adversely affected oocyte maturation, while MT supplementation ameliorated its toxic effects. Specifically, IMI exposure increased oxidative stress (OS), endoplasmic reticulum stress (ERS), and apoptosis, which may affect polar body expulsion rates and blastocyst formation. Also, IMI exposure reduced oocyte cleavage rates and the number of cells in blastocysts. However, all of these toxic effects can be restored after a melatonin supplementation treatment. In conclusion, these results suggest that melatonin has a protective effect on IMI-induced defects during porcine oocyte maturation.

Screening of Toxic Effects of Neonicotinoid Insecticides with a Focus on Acetamiprid: A Review

Recently, neonicotinoids have become the fastest-growing class of insecticides in conventional crop protection, with extensive usage against a wide range of sucking and chewing pests. Neonicotinoids are widely used due to their high toxicity to invertebrates, simplicity, flexibility with which they may be applied, and lengthy persistence, and their systemic nature ensures that they spread to all sections of the target crop. However, these properties raise the risk of environmental contaminations and potential toxicity to non-target organisms. Acetamiprid is a new generation insecticide, which is a safer alternative for controlling insect pests because of its low toxicity to honeybees. Acetamiprid is intended to target nicotinic acetylcholine receptors in insects, but its widespread usage has resulted in negative impacts on non-target animals such as mammals. This review summarizes in vivo and in vitro animal studies that investigated the toxicity of specific neonicotinoids. With summarized data, it can be presumed that certain concentrations of neonicotinoids in the reproductive system cause oxidative stress in the testis; spermatogenesis disruption; spermatozoa degradation; interruptions to endocrine function and Sertoli and Leydig cell function. In the female reproductive system, acetamiprid evokes pathomorphological alterations in follicles, along with metabolic changes in the ovaries.

Induction of apoptosis, oxidative stress, hormonal, and histological alterations in the reproductive system of thiamethoxam-exposed female rats

The present study aimed to investigate the oral toxic effects of 1/10 LD50 and 1/5 LD50 of thiamethoxam (TMX), a neonicotinoid insecticide, on the reproductive system of female Wistar rats. Thirty female rats were divided into three groups and supplied orally with either; saline solution, 1/10 LD50 of TMX (156 mg/kg) or 1/5 LD50 of TMX (312 mg/kg). The daily administration was extended for 30 days. Investigating the parameters of oxidative stress, hormonal levels, histopathological alterations, and the apoptotic markers (P53, BAX, BCL-2, and caspase-3) was performed in the uterus and ovary of rats. Results showed significant changes in the body weight gain, and relative weight of the left and right ovaries and uterus. Moreover, luteinizing hormone (LH), estradiol (ED), and progesterone (PG) serum levels were not significantly altered following TMX oral administration. The level of follicle-stimulating hormone in the TMX-exposed group (156 mg/kg) was significantly increased; however, a significant decrease was observed in TMX-exposed animals (312 mg/kg). TMX induced significant oxidative stress in exposed groups by reducing the activities of superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT), and elevating malondialdehyde (MDA) levels. Following hematoxylin and eosin staining, the microscopic examination revealed deteriorated luteal cells with vacuolation in the corpus luteum, a follicle containing a degenerated oocyte and degeneration/necrosis of the circular muscle layer with a high rate of apoptotic cells in TMX-exposed animals. TMX induced transcriptional alterations in apoptosis-related genes shifting towards the activation of the intrinsic apoptotic pathway. Collectively, results suggest the toxic effect of the TMX on the reproductive health of female Wistar rats.

Imidacloprid and Its Bioactive Metabolite, Desnitro-Imidacloprid, Differentially Affect Ovarian Antral Follicle Growth, Morphology, and Hormone Synthesis In Vitro

Imidacloprid is a neonicotinoid pesticide used in large-scale agricultural systems, home gardens, and veterinary pharmaceuticals. Imidacloprid is a small molecule that is more water-soluble than other insecticides, increasing the likelihood of large-scale environmental accumulation and chronic exposure of non-targeted species. Imidacloprid can be converted to the bioactive metabolite desnitro-imidacloprid in the environment and body. Little is known about the mechanisms by which imidacloprid and desnitro-imidacloprid induce ovarian toxicity. Thus, we tested the hypothesis that imidacloprid and desnitro-imidacloprid differentially affect antral follicle growth and steroidogenesis in vitro. Antral follicles were dissected from the ovaries of CD-1 mice and cultured in media containing vehicle control or 0.2 µg/mL-200 µg/mL of imidacloprid or desnitro-imidacloprid for 96 h. Follicle morphology was monitored, and follicle size was measured every 24 h. At the end of the culture periods, media were used to quantify follicular hormone levels, and follicles were used for gene expression analysis of steroidogenic regulators, hormone receptors, and apoptotic factors. Imidacloprid did not affect follicle growth or morphology compared to the control. Desnitro-imidacloprid inhibited follicle growth and caused follicles to rupture in culture compared to the control. Imidacloprid increased progesterone, whereas desnitro-imidacloprid decreased testosterone and progesterone compared to the control. Desnitro-imidacloprid also changed estradiol compared to the control. At 48 h, IMI decreased the expression of Star, Cyp17a1, Hsd17b1, Cyp19a1, and Esr2 and increased the expression of Cyp11a1, Cyp19a1, Bax, and Bcl2 compared to the control. IMI also changed the expression of Esr1 compared to the control. At 48 h, DNI decreased the expression of Cyp11a1, Cyp17a1, Hsd3b1, Cyp19a1, and Esr1 and increased the expression of Cyp11a1, Hsd3b1, and Bax compared to the control. At 72 h of culture, IMI significantly decreased the expression of Cyp19a1 and increased the expression of Star and Hsd17b1 compared to the control. At 72 h, DNI significantly decreased the expression of Cyp11a1, Cyp17a1, Hsd3b1, and Bax and increased the expression of Esr1 and Esr2. At 96 h, IMI decreased the expression of Hsd3b1, Cyp19a1, Esr1, Bax, and Bcl2 compared to the control. At 96 h, DNI decreased the expression of Cyp17a1, Bax, and Bcl2 and increased the expression of Cyp11a1, Hsd3b1, and Bax compared to the control. Together, these data suggest mouse antral follicles are targets of neonicotinoid toxicity, and the mechanisms of toxicity differ between parent compounds and metabolites.

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.

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.

Effect of Neonicotinoid Pesticides on Japanese Water Systems: Review with Focus on Reproductive Toxicity

Neonicotinoid pesticides (NPs) are neurotoxic substances. They are highly effective as insecticides owing to their water solubility, permeability, and long-lasting activity. These molecules are structurally similar to nicotine and act as nicotinic acetylcholine receptor agonists. The administration of NPs to experimental animals reportedly causes neuromuscular and reproductive disorders. Moreover, recently reported problems caused by NPs include damage to land-dwelling creatures (such as mammals and birds), hydrobiology, and ecosystems. This review summarizes the recent reports on NP concentrations detected in river systems in several Japanese regions. These values were lower than the environmental standard values; however, seasonal variations were observed. Furthermore, reports on NP-induced testicular and ovarian toxicity were examined, revealing that the mechanism of injury is mainly driven by oxidative stress. The use of NPs is declining worldwide, except in Japan; therefore, continuous monitoring remains necessary.

The Influence of Host Aphids on the Performance of Aphelinus asychis

The aphid parasitoid Aphelinus asychis Walker is an important biological control agent against many aphid species. In this study, we examined whether the rearing host aphid species (the pea aphid, Acyrthosiphon pisum and the grain aphid, Sitobion avenae) affect the performance of A. asychis. We found that A. pisum-reared A. asychis showed a significantly larger body size (body length and hind tibia length) and shorter developmental time than S. avenae-reared A. asychis. There was no difference in the sex ratio between them. The longevity of A. pisum-reared A. asychis was also significantly longer than that of S. aveane-reared A. asychis. Furthermore, A. pisum-reared A. asychis presented stronger parasitic capacity and starvation resistance than S. aveane-reared A. asychi. In addition, host aphid alteration experiments showed that A. asychis only takes two generations to adapt to its new host. Taken together, these results revealed that A. pisum is a better alternative host aphid for mass-rearing and releasing of A. asychis. The body size plasticity of A. asychis is also discussed.

Long-Term Effects of Imidacloprid, Thiacloprid, and Clothianidin on the Growth and Development of Eisenia andrei

Recently, the high toxicity of neonicotinoids to the survival and reproduction of adult earthworms has become apparent in standard 56-day toxicity tests. The persistence of some neonicotinoids and/or their repeated application may lead to long-term exposure, possibly also affecting other parts of the life cycle of earthworms. The present study aimed at providing insight into the sublethal effects of imidacloprid, thiacloprid, and clothianidin on juvenile Eisenia andrei exposed for 16 weeks in Lufa 2.2 soil. Significant effects on growth and maturation were observed for all compounds. Exposure to 0.125 mg imidacloprid/kg dry soil and 0.03125 and 0.0625 mg thiacloprid/kg dry soil significantly affected the growth of the earthworms, while significant maturation effects were observed at 0.03125 mg/kg dry soil for imidacloprid and thiacloprid and 0.25 mg clothianidin/kg dry soil. The 16-week no-observed-effect concentrations (NOECs) found in the present study were lower than previously reported NOECs for effects on earthworm reproduction. Predicted environmental concentrations after a single application exceeded the observed NOECs for effects on earthworm maturation in the case of imidacloprid and thiacloprid and for effects on earthworm growth in the case of thiacloprid and clothianidin. Environ Toxicol Chem 2022;41:1686-1695. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

A novel multi-criteria framework for optimizing ecotoxicological effects and human health risks of neonicotinoid insecticides: Characterization, assessment and regulation strategies

The rapid increase of neonicotinoid insecticides (NNIs) leads to the resistance to target organisms and risks to non-target organisms in the ecosystem. Thus, we designed a multi-criteria framework for resistance to target organisms, exposure risks to non-target organisms under spraying and soil or seed treatment scenarios, and ruled out the NNIs on the priority control lists. The resistance and cross-resistance, as well as the toxicity (i.e., acute, chronic, and combined toxicities) were characterized and evaluated. Results showed that the cross-resistance between two NNIs (i.e., CLO and FLU) was 1.8 times higher than their single resistance. A medium to extra-high toxicity level of NNIs was found in non-target organisms. Regulation strategies for NNIs resistance and toxicity were also proposed. The best synergist blocking and control scheme for resistance and toxicity was screened out when three main synergists (i.e., TPP: DEM: PBO) with the ratio of 1:1:1. Four NNIs (i.e., NPM, IMI, ACE, TMX) used in grain crops and six NNIs (i.e., NPM, IMI, ACE, TMX, CLO, THI) used in vegetable crops were determined as the ruled-out pesticides on the priority control lists. This study highlights the adverse effects of NNIs on the ecosystem and human health which should not be overlooked.

Exposure to neonicotinoids and serum testosterone in men, women, and children

Neonicotinoids are the most used pesticides in the world and, despite being harmful to honeybees, they are considered safe for mammals. However, they have been associated with decreasing testosterone levels in several experimental animal models. In the present study, we aimed to determine the association of urinary neonicotinoids with serum testosterone in humans. We analyzed data on 2014 male and female participants to the National Health and Nutrition Examination Survey conducted between 2015 and 2016 aged 6 or older. In linear regression adjusted for age and potential confounders, serum total testosterone was 37.78% lower with 10-fold increase in urinary total neonicotinoids (95% CI: -58.82, -6.00), 20.81% lower with 10-fold increase in urinary 5-hydroxy-imidacloprid (95% CI: -34.94, -3.62) and 25.01% lower with 10-fold increase in urinary n-desmethyl-acetamiprid (95% CI: -39.80, -6.58) among males. Serum free androgen index (FAI) was also decreased with higher urinary n-desmethyl-acetamiprid. In females, serum total testosterone was 32.91% lower with 10-fold increase in urinary total neonicotinoids (95% CI: -54.93, -0.13), 21.32% lower with 10-fold increase in urinary 5-hydroxy-imidacloprid (95% CI: -29.31, -12.42) and 15.42% lower with urinary detection of 5-hydroxy-imidacloprid (95% CI: -22.80, -7.34). FAI was likewise reduced with higher urinary levels of 5-hydroxy-imidacloprid and N-desmethyl-acetamiprid. In conclusion, this study using a sample representative of the US population is the first to report that exposure to neonicotinoids is associated with decreased serum testosterone levels in humans. However, future prospective studies are warranted to confirm these findings.

Mechanisms and histopathological impacts of acetamiprid and azoxystrobin in male rats

Acetamiprid (neonicotinoid insecticide) and azoxystrobin (fungicide) are widespread pesticides used for pest management, but they have the potential for toxicity to mammals. The goal of this study was to look for oxidative stress, metabolic alterations, and reproductive problems in male rats' serum after 2 months of exposure to sub-lethal dosages of acetamiprid and azoxystrobin. Seven classes of male rats were formed: control, 3 groups of acetamiprid (1/10, 1/20, 1/40 LD₅₀), and 3 groups of azoxystrobin (1/10, 1/20, 1/40 LD₅₀) and were orally daily treated (n = 8/group). Our findings revealed that acetamiprid and azoxystrobin disrupted oxidative and metabolic processes in the examined rats throughout 30 and 60 days of testing. The levels of nitric oxide increased significantly, while catalase, a superoxide dismutase enzyme, and glutathione reductase activity were reduced. Serum levels of sex hormones, calcium, and total protein have all dropped substantially in rats. In comparison to the control group, the testis and liver structure, as well as spermatozoa parameters, had distinct histological characteristics. In conclusion, acetamiprid and azoxystrobin exhibit dose- and time-dependent effects on oxidative parameters that cause testis damage.

Urinary neonicotinoid concentrations and pubertal development in Chinese adolescents: A cross-sectional study

BACKGROUND

Animal studies suggest that exposure to certain neonicotinoids may interfere with the normal function of endocrine system in mammals. However, evidence from human studies is limited.

OBJECTIVES

This study conducted a cross-sectional analysis to examine urinary neonicotinoids concentrations in Chinese adolescents and its association with pubertal development.

METHODS

774 urine samples from 439 boys (median age: 13.7 years; 25th-75th percentile: 12.7-14.5 years) and 335 girls (median age: 13.7 years; 25th-75th percentile: 12.7-14.5 years) were collected for determination of ten neonicotinoids (imidacloprid, nitenpyram, acetamiprid, thiacloprid, imidaclothiz, thiamethoxam, clothianidin, dinotefuran, flonicamid, sulfoxaflor) and one metabolite (N-desmethyl-acetamiprid). Urinary creatinine was detected for concentration adjustment. Pubertal development including pubic hair, axillary hair, genitalia (boys), testicular volume (boys) and breast (girls) assessed by Tanner stages and others (spermarche, facial hair for boys and menarche for girls) were obtained by physical examination and questionnaire. Logistic and bayesian kernel machine regression were used to investigate the association between neonicotinoids concentrations and pubertal developments.

RESULTS

High detection rates ranged from 72.0% to 100.0% for all neonicotinoids. Boys and girls with thiacloprid concentration at the >75th percentile had lower stage of genitalia development (OR: 0.83, 95% CI: 0.33-0.93) and higher stage of axillary hair development (OR: 1.46, 95% CI: 1.12-3.41), respectively, compared with those at the <25th percentile. The estimate change in genitalia stage was significantly different at or above the 75th percentile concentration of neonicotinoids mixture compared to the 50th percentile concentration. No associations were found between other urinary neonicotinoids and other indicators of puberty.

CONCLUSIONS

Higher thiacloprid concentration was associated with delayed genitalia development in boys and early axillary hair development in girls. Neonicotinoids mixture was negatively associated with genitalia stage in the joint effect. Given the characteristic of the cross-sectional study, our results need further confirmation of the causal relationship.

The edible plant Amaranthus hybridus (Amaranthaceae) prevents the biochemical, histopathological and fertility impairments in colibri®-treated female rats

Colibri® a commercial formulation of Imidacloprid severely impairs the reproductive function. This study aimed at evaluating the preventive effects of Amaranthus hybridus on the reproductive toxicity of colibri® in female rats. Eighty rats (n = 10/group) were orally treated with colibri® (22.5 mg/kg) and co-administered with either aqueous or methanolic extracts of A. hybridus (55 or 110 mg/kg) within four weeks. Control animals received either distilled water (10 ml/kg), clomiphene citrate or vitamin E. Starting from day 18 of treatment till the end, half of animals in each group (n = 5) was used for the fertility test whereas the remaining rats were kept under treatment until sacrifice. Blood, ovaries, uterus and vagina were collected after sacrifice for measurement of sexual hormones, oxidative stress markers and histological assessment. Exposure of female rats to colibri® was followed by a significant reduction (p < 0.05) in the ovarian and uterine weights, LH, FSH, estradiol and progesterone levels as well as ovarian superoxide dismutase, catalase and peroxidase activities. Moreover, alteration of ovaries, uteri and vagina histology, increase in MDA concentration, decrease in fertility and parturition indices and, pup's viability were recorded. Co-administration of colibri® and plant extracts significantly (p < 0.05-0.001) prevented the above-mentioned damages through biochemical parameter regulations. These results suggest that A. hybridus exerts a preventive effect against colibri®-induced female reproductive toxicity.

Rapid Quantitative Determination of Multiple Pesticide Residues in Mango Fruits by Surface-Enhanced Raman Spectroscopy

Imidacloprid, acephate, and carbaryl are common insecticides that are extensively used in planting mango, a well-known fruit in Vietnam, to ease mango hopper issues. The accurate detection of pesticide residues is critical for mango export to meet quality criteria. This study developed a novel SERS platform by using polydimethylsiloxane (PDMS) to simulate the rose petal structure incorporated with a silver coating layer and silver nanoparticles (AgNPs) to detect imidacloprid, acephate, and carbaryl in mango fruits. In this paper, the rose petal PDMS/Ag-AgNPs replica was considered the most efficient substrate for SERS measurement with an EF of 4.7 × 107. The Raman spectra of the three insecticides obtained from the PDMS/Ag-AgNPs substrate were clearly observed with their characteristic peaks of 1105 cm−1 for imidacloprid, 1083 cm−1, and 1579 cm−1 for acephate, and 727 cm−1 and 1378 cm−1 for carbaryl. The application of PDMS/Ag-AgNPs substrate in quantitative analysis of the three pesticides in mango fruit was evaluated. As a result, the limit of detection was 0.02 mg/kg for imidacloprid, 5 × 10−5 mg/kg for acephate, and 5 × 10−3 mg/kg for carbaryl. The SERS result also revealed that the pesticide residues in the mango sample were within an acceptable limit. This suggested the possibility of the rose petal PDMS/Ag-AgNPs replica for rapid quantification of pesticide residues not only in mango fruit but also in many other agricultural products.

Characteristics of neonicotinoid and metabolite residues in Taiwanese tea leaves

BACKGROUND

Neonicotinoids are widely used insecticides, and tea is a popular non-alcoholic beverage in Taiwan. However, the levels of neonicotinoids in Taiwanese tea leaves remain unclear. Therefore, this study aims to understand the characteristics of neonicotinoid and metabolite residues in Taiwanese tea leaves.

METHODS

In this study, 12 tea leaf samples were collected in Taiwan and extracted by solid-phase extraction before analysis by liquid chromatography-tandem mass spectrometry. In addition, the levels of neonicotinoids were compared with the maximum residue level standards from other countries.

RESULTS

In Taiwanese tea leaves, five neonicotinoids and seven metabolites were detected. Different tea species influenced the levels of neonicotinoids and their metabolites in the present study. Moreover, the levels of neonicotinoids and their metabolites in partially fermented leaves were higher than in completely fermented leaves. In Jin-Xuan tea, the levels of neonicotinoids and their metabolites in most winter-harvested teas were lower than in summer-harvested teas.

CONCLUSION

The residue levels of neonicotinoids and their metabolites were detectable in Taiwanese tea leaves. Moreover, different tea species, manufacturing processes, and harvest seasons might influence the levels of these pesticides. Therefore, the government should monitor the use of neonicotinoids. © 2021 Society of Chemical Industry.

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.

Fucoidan Protects against Acute Sulfoxaflor-Induced Hematological/Biochemical Alterations and Oxidative Stress in Male Mice

Fucoidan is a sulfated polysaccharide which can be found among a number of macroalgea species. It has a broad spectrum of biological activities including anti-oxidant, anti-tumor, immunoregulation, anti-viral and anti-coagulant. The current study was performed to investigate possible protective effects of fucoidan for sulfoxaflor-induced hematological/biochemical alterations and oxidative stress in the blood of male Swiss albino mice. For this purpose, sulfoxaflor was administered at a dose of 15 mg/kg/day (1/50 oral LD₅₀), and fucoidan was administered at a dose of 50 mg/kg/day by oral gavage alone and combined for 24 h and 7 days. Hematological parameters (RBC, HGB, HCT, MCV, MCH, MCHC, Plt, WBC, Neu, Lym and Mon), serum biochemical parameters (AST, ALT, GGT, LDH, BUN, Cre and TBil), and serum oxidative stress/antioxidant markers (8-OHdG, MDA, POC and GSH) were analyzed. The results indicated that sulfoxaflor altered hematological and biochemical parameters and caused oxidative stress in mice; fucoidan ameliorated some hematological and biochemical parameters and exhibited a protective role as an antioxidant against sulfoxaflor-induced oxidative stress.

Fucoidan Modulated Oxidative Stress and Caspase-3 mRNA Expression Induced by Sulfoxaflor in the Brain of Mice

The current study aimed to investigate the role of fucoidan in the oxidative and apoptotic effects of sulfoxaflor, a neonicotinoid sulfoximine insecticide, in the brain of Swiss albino mice (Mus musculus). Sulfoxaflor and fucoidan were administered to mice at doses of 15 mg/kg/day (1/50 oral LD50) and 50 mg/kg/day, respectively, by oral gavage for 24 h or 7 days. The tGSH, TBARS and protein levels, and GPx, GR, and GST enzyme activities were determined by spectrophotometric methods. Caspase-3 gene expression level was determined by RT-PCR. Data analysis showed that brains of sulfoxaflor-treated mice exhibited higher TBARS levels; GPx, GR, and GST enzyme activities; and caspase-3 expression levels, as well as lower levels of tGSH. Co-administration of fucoidan and sulfoxaflor reduced the TBARS levels, increased tGSH levels, and increased GPx, GR, and GST enzyme activities. Fucoidan also decreased the sulfoxaflor-induced up-regulation of caspase-3 mRNA expression. Results of the present study showed that sulfoxaflor caused oxidative stress by inducing lipid peroxidation and altering GSH-dependent antioxidants in the brain of mice. In addition, sulfoxaflor may trigger apoptotic cell death shown by the up-regulation of caspase-3. Fucoidan treatment modulated all the aforementioned alterations in the brain of mice. It was concluded that fucoidan might have antioxidant effects that support the GSH-dependent antioxidant system and can play a modulator role in oxidative stress and caspase-3 expression in the brain of sulfoxaflor treated-mice.

Thiamethoxam-induced oxidative stress, lipid peroxidation, and disturbance of steroidogenic genes in male rats: Palliative role of Saussurea lappa and Silybum marianum

Thiamethoxam (TMX) belongs to the neonicotinoid insecticide family and may evoke marked endocrine disruption. In this study, the reproductive toxicity of TMX on male rats was assessed along with the ability of Saussurea lappa (costus roots) and/or Silybum marianum extract (SM) to alleviate TMX toxicity. Male rats were allocated to seven groups and orally treated daily for 4 weeks: Control (saline), Costus (200 mg/kg), SM (150 mg/kg), TMX (78.15 mg/kg), TMX-costus, TMX-SM, and TMX-costus-SM (at the aforementioned doses). Compared with control group, TMX administration induced reductions in testicular levels of glutathione and antioxidant activities of SOD and CAT. In addition, TMX-exposed rats showed lower serum testosterone hormonal levels as well as higher malondialdehyde and nitric acid levels were detected in TMX-administered rats. On a molecular basis, mRNA expressions of StAR, CYP17a, 3β-HSD, SR-B1, and P450scc genes were significantly down-regulated in TMX group, whereas the expression of LHR and aromatase genes was up-regulated. Moreover, TMX-induced testicular damage was confirmed by histopathological screening. Importantly, however, the administration of either costus roots or SM significantly alleviated all aforementioned TMX-induced changes, indicating the effective antioxidant activities of these plant products. Interestingly, simultaneous treatment with costus root and SM provided better protection against TMX reproduction toxicity than treatment with either agent alone.

An integrated approach, based on mass spectrometry, for the assessment of imidacloprid metabolism and penetration into mouse brain and fetus after oral treatment

Imidacloprid is an insecticide belonging to neonicotinoids, a class of agonists of the nicotinic acetylcholine receptors that shows higher affinities in insects compared to mammals. However, recent evidence show that neonicotinoids can bind to the mammalian receptors, leading to detrimental responses in cultured neurons. We developed an analytical strategy which uses mass spectrometry with multiple reaction monitoring (targeted approach) and high-resolution acquisitions (untargeted approach), which were applied to quantify imidacloprid and to identify its metabolites in biological tissues after oral treatments of mice. Mouse dams were treated with doses from 0.118 mg/kg bw day up to 41 mg/kg day between gestational days 6-9. Results showed quantifiable levels of imidacloprid in plasma (from 30.48 to 5705 ng/mL) and brain (from 20.48 to 5852 ng/g) of treated mice, proving the passage through the mammalian blood-brain barrier with a high correspondence between doses and measured concentrations. Untargeted analyses allowed the identification of eight metabolites including imidacloprid-olefin, hydroxy-imidacloprid dihydroxy-imidacloprid, imidacloprid-nitrosimine, desnitro-imidacloprid, 6-chloronicotinic acid, 5-(methylsulfanyl)pyridine-2-carboxylic acid and N-imidazolidin-2-ylidenenitramide in plasma and brain. Moreover, analysis of embryonic tissues after oral treatment of mouse dams showed detectable levels of imidacloprid (816.6 ng/g after a dose of 4.1 mg/Kg bw day and 5646 ng/g after a dose of 41 mg/Kg bw day) and its metabolites, proving the permeability of the placenta barrier. Although many studies have been reported on the neurotoxicity of neonicotinoids, our study paves the way for a risk assessment in neurodevelopmental toxicity, demostrating the capability of imidacloprid and its metabolites to pass the biological barriers.

Simultaneous quantification of imidacloprid and its metabolites in tissues of mice upon chronic low-dose administration of imidacloprid

This study aimed to (i) develop a sensitive method for simultaneous detection and quantification of imidacloprid (IMI) and seven of its metabolites in tissue specimens, and to (ii) determine the biodistribution of the IMI compounds in tissues of C57BL/6J male mice; after exposure to 0.6 mg/kg bw/day of IMI (10% of no observable adverse effect level of IMI) through a powdered diet for 24 weeks. We successfully developed a method which was accurate (recoveries were ≥ 70% for most compounds), sensitive (LODs ≤ 0.47 ng/mL and LOQs ≤ 1.43 ng/mL were recorded for all detected compounds, R2 ≥ 0.99) and precise (RSDs ≤ 20%) for routine analysis of IMI and seven of its metabolites in blood and various tissue matrices. After bio-distributional analysis, IMI and five of its metabolites were detected in mice. Brain, testis, lung, kidney, inguinal white adipose tissue and gonadal white adipose tissue mainly accumulated IMI, blood and mesenteric white adipose tissue mainly accumulated IMI-olefin; liver mainly accumulated desnitro-IMI; pancreas predominately accumulated 4-hydroxy-IMI. The desnitro-dehydro-IMI and the desnitro-IMI metabolites recorded tissue-blood concentration ratios ≥ 1.0 for testis, brain, lung and kidney. The cumulative levels of the six detected IMI compounds (Σ6 IMI compounds) were found in the decreasing order: blood > testis > brain > kidney > lung > iWAT > gWAT > mWAT > liver > pancreas. Altogether, this study provided essential data needed for effective mechanistic elucidation of compound-specific adverse outcomes associated with chronic exposures to IMI in mammalian species.

Neurotoxic Effects of Neonicotinoids on Mammals: What Is There beyond the Activation of Nicotinic Acetylcholine Receptors?-A Systematic Review

Neonicotinoids are a class of insecticides that exert their effect through a specific action on neuronal nicotinic acetylcholine receptors (nAChRs). The success of these insecticides is due to this mechanism of action, since they act as potent agonists of insect nAChRs, presenting low affinity for vertebrate nAChRs, which reduces potential toxic risk and increases safety for non-target species. However, although neonicotinoids are considered safe, their presence in the environment could increase the risk of exposure and toxicity. On the other hand, although neonicotinoids have low affinity for mammalian nAChRs, the large quantity, variety, and ubiquity of these receptors, combined with its diversity of functions, raises the question of what effects these insecticides can produce in non-target species. In the present systematic review, we investigate the available evidence on the biochemical and behavioral effects of neonicotinoids on the mammalian nervous system. In general, exposure to neonicotinoids at an early age alters the correct neuronal development, with decreases in neurogenesis and alterations in migration, and induces neuroinflammation. In adulthood, neonicotinoids induce neurobehavioral toxicity, these effects being associated with their modulating action on nAChRs, with consequent neurochemical alterations. These alterations include decreased expression of nAChRs, modifications in acetylcholinesterase activity, and significant changes in the function of the nigrostriatal dopaminergic system. All these effects can lead to the activation of a series of intracellular signaling pathways that generate oxidative stress, neuroinflammation and, finally, neuronal death. Neonicotinoid-induced changes in nAChR function could be responsible for most of the effects observed in the different studies.

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.

Comparison of the toxicity of pure compounds and commercial formulations of imidacloprid and acetamiprid on HT-29 cells: Single and mixture exposure

Neonicotinoids, which are widely used worldwide, including in Turkey, are an insecticide group that are synthetic derivatives of nicotine. Recently, they have attracted attention due to their toxic effects on non-target organisms, especially bees. Numerous studies have shown that neonicotinoids have been found in detectable levels in the environment and cause various undesirable effects on living organisms, including humans and other mammals. In this study, the possible toxic effects of imidacloprid and acetamiprid, commonly used neonicotinoids, are investigated by their pure forms and commercial formulations on HT-29 cells with individual and combined exposures. According to our results, imidacloprid and acetamiprid induced cytotoxicity by caspase-mediated apoptosis, mitochondrial membrane depolarization, DNA damage, and oxidative stress under these experimental conditions. It is worth mentioning low doses of DNA damage, mixture exposure causes toxic effects at lower concentrations than individual exposure, and formulation groups are at the forefront of toxicity formation, though this varies depending on the parameters.

Measuring urinary concentrations of neonicotinoid insecticides by modified solid-phase extraction-ultrahigh performance liquid chromatography-tandem mass spectrometry: Application to human exposure and risk assessment

Neonicotinoid insecticides are the most widely used insecticides in the world. However, some experiments in vivo and vitro have shown association between neonicotinoids exposure and adverse effects in non-target mammals. The aims of this study were to 1) develop a robust method for simultaneous quantification of urinary neonicotinoids with a wide water solubility range by modified solid-phase extraction-ultrahigh performance liquid chromatography- tandem mass spectrometry and 2) quantify the concentrations of ten neonicotinoids in 386 adolescents in Chongqing of Southwest China by using the developed method and assess health risks of exposure to neonicotinoids. The introduction of extractive crystallization effectively removed interfering inorganic salts and improved the sensitivity of the method. The mean recoveries of all the analytes were satisfactory in the range of 89.1-104.8% and the limits of detection ranged from 0.001 to 0.02 ng/mL. The developed method was sensitive, accurate and suitable for trace detection and batch analysis in biomonitoring-based studies. Of the ten examined neonicotinoids, acetamiprid had the highest geometric mean concentration (49.43 μg/g creatinine), followed by clothianidin (5.01), imidacloprid (3.80), thiamethoxam (3.24), thiacloprid (2.25), nitenpyram (1.79), dinotefuran (1.76), sulfoxaflor (1.65), imidaclothiz (1.28) and flonicamid (1.01). High detection rates of neonicotinoids (79.3-100.0%) indicated a ubiquitous adolescents' exposure to neonicotinoids in urban areas of Chongqing. Nevertheless, hazard quotient and hazard index data exhibited a low health risk caused by the individual and cumulative exposure to neonicotinoids on the basis of the reference limit values recommended by the U.S. Environmental Protection Agency and the National Food Safety Standard of China.

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.

Effects of in utero and lactational exposure to the no-observed-adverse-effect level (NOAEL) dose of the neonicotinoid clothianidin on the reproductive organs of female mice

Recently, developmental exposure to clothianidin (CLO) has been shown to cause reproductive toxicity in male mice, but the effects in female mice remain to be clarified. Pregnant C57BL/6N mice were given a no-observed-adverse-effect-level (NOAEL) dose of CLO until weaning. We then examined ovaries of 3- or 10-week-old female offspring. In the CLO-administered group, morphological changes, a decrease in the immunoreactivity of the antioxidant enzyme glutathione peroxidase 4 (GPx4), and activation of genes in the steroid hormone biosynthesis pathway were observed in 3-week-old mice, and decreases of GPx4 immunoreactivity, 17OH-progesterone and corticosterone levels were observed in 10-week-old mice, along with high rates of infanticide and severe neglect, providing new evidence that developmental exposure to CLO affects juvenile and adult mice differently.

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.

Translocation and metabolism of imidacloprid in cabbage: Application of 14C-labelling and LC-QTOF-MS

Imidacloprid (IMI) is a widely used neonicotinoid insecticide effective against sucking and some chewing insects. Translocation and metabolism of IMI in plants are related to food safety. In this study, ¹⁴C-labeled IMI was used to investigate its translocation, transformation, radioactive IMI metabolites and possible metabolic pathways in cabbage. The amount of IMI accumulated in the edible part of cabbage accounted for 80.3-95.4% of the applied amounts by foliar application. There was a tendency to transport from edible parts to inedible parts. The proportions of extractable IMI decreased gradually from 92.4% to 83.0% in edible parts, greater than that in inedible parts over the experiment (0-19 days), while the bound residues showed an opposite trend. The half-life of IMI was determined as 33.0 and 63.0 days in the edible parts and whole plant, respectively. Five radioactive components including the parent IMI were detected by HPLC-LSC. The relative content of M1 was less than 0.01 mg kg^-1, which was not required to identify according to the metabolic scheme proposed by the US Environmental Protection Agency. The metabolites N-nitro(1-6-chloro-3-pyridylmethyl)-4,5-dihydroxyimidazol-2-imine (M2), N-nitro(1-6-chloro-3-pyridylmethyl)-4/5-hydroxyimidazole-2-imine (M3) and 1/3-(1-6-chloro-3-pyridylmethyl)-2,4-imidazodione (M4) were identified by LC-QTOF-MS. The primary metabolism of IMI in cabbage included hydrolysis and oxidation. The residue level and daily intake values of IMI in cabbage were estimated to be 0.033-0.078 mg kg^-1 and 9.56-20.01 ng d^-1 kg^-1, respectively, which were far below the maximum residue level and allowable daily intake values.

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.

Exposure Level of Neonicotinoid Insecticides in the Food Chain and the Evaluation of Their Human Health Impact and Environmental Risk: An Overview

Neonicotinoid insecticides (neonics) were the most rapidly growing class of insecticides over the past few decades, and are used mainly for vegetables, fruits, and grains. Although neonics exhibit lower toxicity in mammals and humans compared to traditional insecticides, increasing numbers of studies are demonstrating that neonics may accumulate in the food chain and environmental media. Long-term exposure to neonics may raise potential risks to animals and even to humans. The present report reviews the development, application, and prohibition of neonics in the farmland ecosystem, and summarizes the exposure level and harmful effects of these insecticides in the food chain. In addition, the present review analyzes and summarizes the evaluation of the human health impact and environmental risk of the neonics, and overviews the unresolved problems and future research directions in this field. The aim of the present report was to review the exposure level, potential toxicity, human health impact, and environmental risk assessment of neonics in various media in order to provide reliable technical support for strengthening the environmental and food safety supervision and green pesticide designing.

Assessment of imidacloprid related exposure using imidacloprid-olefin and desnitro-imidacloprid: Neonicotinoid insecticides in human urine in Wuhan, China

While neonicotinoid insecticides (NNIs) have been widely used worldwide, limited studies have measured specific metabolites of imidacloprid (IMI, the most commonly used NNI) in human urine. To better understand human exposure to NNIs, 10 parent compounds, and 6 of their metabolites were analyzed in 408 urine samples collected from 129 healthy adults in Wuhan, Central China, during autumn and winter of 2018. These specimens included repeated urine samples taken in 3 d from 75 volunteers. The urinary concentrations of desnitro-imidacloprid (DN-IMI), imidacloprid-olefin (IMI-olefin), and desmethyl-acetamiprid (DM-ACE) were higher (4-40 times) than those of their parent compounds (IMI and acetamiprid, ACE). DN-IMI and IMI-olefin accounted for 92% of the urinary Σ₃IMI (the sum of IMI and its specific metabolites measured). Positive correlations (r) were observed between DN-IMI and IMI (0.50), IMI-olefin and IMI (0.75), and DM-ACE and ACE (0.53). Good to excellent inter-day reliabilities (unadjusted intraclass correlation coefficients) were observed for IMI-olefin (0.61) and DM-ACE (0.81), while moderate inter-day reliability was observed for DN-IMI (0.43). The urinary NNI concentrations were significantly higher in autumn than in winter, and higher in urban areas than in rural areas, while no significant gender or age-related differences were observed. To our knowledge, this is the first report on DN-IMI and IMI-olefin in human urine.

Integrated Approach to Evaluate the Association between Exposure to Pesticides and Idiopathic Premature Thelarche in Girls: The PEACH Project

Several pesticides are recognized as endocrine-disrupting chemicals (EDCs) since they can interfere with the dysregulation of sexual, thyroid and neuro-endocrine hormones. Children are particularly vulnerable to the adverse effects of EDCs due to their developmental stage, peculiar lifestyle and dietary habits. In this context, the exposure to pesticides represents an important risk factor associated with early development. This study deals with the possible association between exposure to pesticides and idiopathic premature thelarche in girls from areas of intensive agriculture practice in the Centre of Italy. An integrated approach was set up, including: (i) a case-control study on girls with idiopathic premature thelarche; (ii) the evaluation of multiple pesticides exposure in girls; (iii) the evaluation of multiple pesticides in food; (iv) the dietary intake of pesticide residues; (v) the assessment of toxicological effects of widely used pesticides by in vitro model. Data integration will provide an estimate of the predictive risk of potential effects on girls' health, linked to dietary intake.

Effect of agricultural pesticide on precocious puberty in urban children: an exploratory study

BACKGROUND

The incidence of precocious puberty has increased throughout the 20th century. The association between precocious puberty and endocrine disrupting chemicals including agricultural pesticides has been a subject of global study, but human data are lacking.

PURPOSE

We investigated the relationship between agricultural pesticides and the development of precocious puberty.

METHODS

We enrolled 60 female subjects at Severance Children's Hospital from December 2015 to January 2017. Of them, 30 were diagnosed with precocious puberty, while the other 30 prepubertal girls were enrolled as normal controls. We investigated their clinical characteristics and analyzed the urinary levels of 320 different agricultural pesticides.

RESULTS

Agricultural pesticide was detected in one of 30 patients with precocious puberty (3.3%) versus 2 of 30 girls in the normal control group (3.3% vs. 6.7%, P=0.554). Dinotefuran, a neonicotinoid-class insecticide, was detected in the samples of all 3 positive subjects.

CONCLUSION

Our results showed no relationship between agricultural pesticides and the development of precocious puberty. Larger sample sizes and robustly controlled variables are necessary to further investigate this topic.