The human and ecological risks of neonicotinoid insecticides in soils of an agricultural zone within the Pearl River Delta, South China

Neonicotinoid insecticides in a large-scale agricultural basin system-Use, emission, transportation, and their contributions to the ecological risks in the Pearl River Basin, China

Neonicotinoid pollution has increased rapidly and globally in recent years, posing significant risks to agricultural areas. Quantifying use and emission, transport and fate of these contaminants, and risks is critical for proper management of neonicotinoids in river basin. This study elucidates use and emissions of neonicotinoid pesticides in a typical large-scale agriculture basin of China, the Pearl River Basin, as well as the resulting agricultural non-point source pollution and related ecological risks using market surveys, data analysis, and the Soil and Water Assessment Tool. Neonicotinoid use in the basin was estimated at 1361 t in 2019, of which 83.1 % was used in agriculture. After application, approximately 99.1 t neonicotinoids were transported to the Pearl River, accounting for 7.2 % of the total applied. Estimated aquatic concentrations of neonicotinoids showed three seasonal peaks. Several distinct groups of neonicotinoid chemicals can be observed in the Pearl River, as estimated by the model. An estimated 3.9 % of the neonicotinoids used were transported to the South China Sea. Based on the present risk assessment result, several neonicotinoids posed risks to aquatic organism. Therefore, the use of alternative products and/or reduced use is deemed necessary. This study provides novel insights into the fate and ecological risks of neonicotinoid insecticides in large-scale watersheds, and underscores the need for greater efficiency of use and extensive environmental monitoring.

High-throughput screening of 222 pesticides in road environments in a megacity of northern China: A new approach to urban population exposure

A large number of pesticides have been widely manufactured and applied, and are released into the environment with negative impact on human health. Pesticides are largely used in densely populated urban environments, in green zones, along roads and on private properties. In order to characterize the potential exposure related health effects of pesticide and their occurrence in the urban environment, 222 pesticides were screened and quantified in 228 road dust and 156 green-belt soil samples in autumn and spring from Harbin, a megacity in China, using GC-MS/MS base quantitative trace analysis. The results showed that a total of 33 pesticides were detected in road dust and green-belt soil, with the total concentrations of 650 and 236 ng/g (dry weight = dw), respectively. The concentrations of pesticides in road dust were significantly higher than that in green-belt soil. Pesticides in the environment were influenced by the seasons, with the highest concentrations of insecticides in autumn and the highest levels of herbicides in spring. In road dust, the concentrations of highways in autumn and spring (with the mean values of 94.1 and 68.2 ng/g dw) were much lower than that of the other road classes (arterial roads, sub-arterial roads and branch ways). Whereas in the green-belt soil, there was no significant difference in the concentration of pesticides between the different road classes. A first risk assessment was conducted to evaluate the potential adverse health effects of the pesticides, the results showed that the highest hazard index (HI) for a single pesticide in dust and soil was 0.12, the hazard index for children was higher than that for adults, with an overall hazard index of less than 1. Our results indicated that pesticide levels do not have a significant health impact on people.

Residual distribution and risk assessment of neonicotinoids in urban green space soils of the pearl river delta, South China: A socioeconomic analysis

Urban green spaces are the soil component in cities that interacts most closely with humans. This study investigated the residues of seven neonicotinoids (NEOs) in soils from urban green spaces within the Pearl River Delta (PRD) region and analyzed the correlation between the residue characteristics and the region's economic development. Notably, we introduced the Nemerow Index method, a comprehensive approach, to quantify the overall pollution level of NEOs in the soil of urban park green spaces and utilized this to assess the cumulative exposure probability risks for different populations in this scenario. We found that: (1) The soil of urban park green spaces exhibited varying degrees of NEOs contamination (Σ7NEOs: N.D.-137.31; 6.25 μg/kg), with imidacloprid and clothianidin constituting the highest proportions (89.46 % and 83.60 %); (2) The residual levels of NEOs in Children's Park were significantly higher than those in community parks within Guangzhou, with an average value of 13.30 μg/kg compared to 3.30 μg/kg; (3) The residual characteristics of NEOs exhibited a positive correlation with regional economic development; specifically, the per capita GDP well correlated with IMIRPF, a summation of seven NEOs in imidacloprid equivalents via relative potency factors (R2 =0.86). Regions with higher economic development typically exhibited elevated IMIRPF levels; (4) The fitted cumulative probability distributions for average daily exposure doses revealed that children's exposure was an order of magnitude higher than adults'. Despite this, the exposure risks for both groups remained within acceptable limits.

Spatiotemporal distribution, risk levels, and transport variations in neonicotinoids and fipronil and its metabolites cross a river-to-sea continuum

Neonicotinoids (NEOs) and fipronil are widely used in pest control, but their spatiotemporal distribution and risk levels in the "river-estuary-bay" system remain unclear. Between 2018 and 2021, 148 water samples from rivers to inshore and offshore seawater in Laizhou Bay, China were collected to investigate the presence of eight NEOs and fipronil and its metabolites (FIPs). Significant seasonal variations in NEOs were observed under the influence of different cultivation practices and climatic conditions, with higher levels in the summer than in the spring. The average concentrations of total neonicotinoids (ΣNEOs) and ∑FIPs decreased from rivers (63.64 ng/L, 2.41 ng/L) to inshore (22.62 ng/L, 0.14 ng/L) and offshore (4.48 ng/L, 0.10 ng/L) seawater of Laizhou Bay. The average concentrations of ΣNEOs decreased by 85.3 % from 2018 to 2021. The predominant insecticides in the study area were acetamiprid, thiamethoxam, imidacloprid, and fipronil sulfone, with a gradual shift toward low-toxicity and environmentally friendly species over time. Influenced by agricultural intensity, ∑NEOs were mostly distributed in the Yellow River, Xiaoqing River, and their estuaries, where they pose chronic ecological risks. However, FIP exhibited high risk in certain rivers and sewage treatment plants owing to the use of animal repellents or landscape gardening insecticides. This study provides evidence of the transfer of NEOs and FIPs from rivers to the ocean and also clarifies their transition dynamics and changes in risk levels from rivers to oceans. Additionally, the study offers data support for identifying critical pesticide control areas.

Mapping pesticide residues in soil for China: Characteristics and risks

The widespread application of pesticides in China has led to the accumulation of residues in soil. However, few regional studies have fully elucidated the characteristics of pesticide residues in soil (PRS) and the associated risks to the ecosystem and human health on a national level. Therefore, this study aims to compile a dataset on PRS in China from 2006 to 2020 and analyze the interactions and impacts between PRS and the environment. The average concentration of PRS in China was 243.96 μg/kg which was lower than the levels reported in Euro-Americans and other nations. This study revealed PRS in China predominantly originates from organochlorine pesticide residues, with DDTs and HCHs being significant contributors. Despite the high intensity of pesticide application in the Southeast China, PRS concentrations were comparable to those in the Northeast, due to environmental factors that favor pesticide degradation in the Southeast. Both legacy and in-use pesticides were transported by surface runoff or air current, resulting in their accumulation in soil of the lower Yangtze River basin or the piedmont soil of Qinling Mountains, respectively. The average soil environment carrying capacity of PRS in China was -69.5 kg. The ecological risk contributed by PRS in China was mainly at a negligible level. Carcinogenic risks of PRS to adults (4.6 ×10-4) and children (6 ×10-4) exceeded the tolerable thresholds (10-5) by a small margin.

Neonicotinoids as emerging contaminants in China's environment: a review of current data

Neonicotinoids (NEOs), the most widely used class of insecticides, are pervasive in the environment, eliciting concerns due to their hydrophilicity, persistence, and potential ecological risks. As the leading pesticide consumer, China shows significant regional disparities in NEO contamination. This review explores NEO distribution, sources, and toxic risks across China. The primary NEO pollutants identified in environmental samples include imidacloprid, thiamethoxam, and acetamiprid. In the north, corn cultivation represents the principal source of NEOs during wet seasons, while rice dominates in the south year-round. The high concentration levels of NEOs have been detected in the aquatic environment in the southern regions (130.25 ng/L), the urban river Sects. (157.66 ng/L), and the downstream sections of the Yangtze River (58.9 ng/L), indicating that climate conditions and urban pollution emissions are important drivers of water pollution. Neonicotinoids were detected at higher levels in agricultural soils compared to other soil types, with southern agricultural areas showing higher concentrations (average 27.21 ng/g) than northern regions (average 12.77 ng/g). Atmospheric NEO levels were lower, with the highest concentration at 1560 pg/m3. The levels of total neonicotinoid pesticides in aquatic environments across China predominantly exceed the chronic toxicity ecological threshold of 35 ng/L, particularly in the regions of Beijing and the Qilu Lake Basin, where they likely exceed the acute toxicity ecological threshold of 200 ng/L. In the future, efforts should focus on neonicotinoid distribution in agriculturally developed regions of Southwest China, while also emphasizing their usage in urban greening and household settings.

Pharmacotherapeutic potential of malvidin to cure imidacloprid induced hepatotoxicity via regulating PI3K/AKT, Nrf-2/Keap-1 and NF-κB pathway

Imidacloprid (IMI) is one of the top-notch insecticides that adversely affects the body organs including the liver. Malvidin (MAL) is a natural flavonoid which exhibits a wide range of pharmacological properties. This research was designed to evaluate the protective ability of MAL to counteract IMI instigated liver toxicity in rats. Thirty-two rats were divided into four groups including control, IMI (5mg/kg), IMI (5mg/kg) + MAL (10mg/kg) and MAL (10mg/kg) alone treated group. The recommended dosages were administrated through oral gavage for 4 weeks. It was revealed that IMI intoxication disrupted the PI3K/AKT and Nrf-2/Keap-1 pathway. Furthermore, the activities of catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), heme-oxygenase-1 (OH-1) and glutathione reductase (GSR) were reduced while upregulating reactive oxygen species (ROS) and malondialdehyde (MDA) levels after IMI treatment. Moreover, IMI poisoning increased the levels of ALT (Alanine aminotransferase), AST (Aspartate transaminase), and ALP (Alkaline phosphatase) while reducing the levels of total proteins and albumin in hepatic tissues of rats. Besides, IMI administration escalated the expressions of Bcl-2-associated protein x (Bax) and cysteine-aspartic acid protease-3 (Caspase-3) while downregulating the expressions of B-cell lymphoma 2 (Bcl-2). Similarly, IMI intoxication, increased the levels of Interleukin-6 (IL-6), Nuclear factor kappa-B (NF-κB), Interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the activity of cyclooxygenase-2 (COX-2). Furthermore, IMI disrupted the normal architecture of hepatic tissues. However, MAL treatment remarkably protected the liver tissues via regulating abovementioned disruptions.

The fate and transport of neonicotinoid insecticides and their metabolites through municipal wastewater treatment plants in South China

Neonicotinoid insecticides (NEOs) have gained widespread usage as the most prevalent class of insecticides globally and are frequently detected in the environment, posing potential risks to biodiversity and human health. Wastewater discharged from wastewater treatment plants (WWTPs) is a substantial source of environmental NEOs. However, research tracking NEO variations in different treatment units at the WWTPs after being treated by the treatment processes remains limited. Therefore, this study aimed to comprehensively investigate the fate of nine parent NEOs (p-NEOs) and five metabolites in two municipal WWTPs using distinct treatment processes. The mean concentrations of ∑NEOs in influent (effluent) for the UNITANK, anaerobic-anoxic-oxic (A2/O), and cyclic activated sludge system (CASS) processes were 189 ng/L (195 ng/L), 173 ng/L (177 ng/L), and 123 ng/L (138 ng/L), respectively. Dinotefuran, imidacloprid, thiamethoxam, acetamiprid, and clothianidin were the most abundant p-NEOs in the WWTPs. Conventional wastewater treatment processes were ineffective in removing NEOs from wastewater (-4.91% to -12.1%), particularly major p-NEOs. Moreover, the behavior of the NEOs in various treatment units was investigated. The results showed that biodegradation and sludge adsorption were the primary mechanisms responsible for eliminating NEO. An anoxic or anaerobic treatment unit can improve the removal efficiency of NEOs during biological treatment. However, the terminal treatment unit (chlorination disinfection tank) did not facilitate the removal of most of the NEOs. The estimated total amount of NEOs released from WWTPs to receiving waters in the Pearl River of South China totaled approximately 6.90-42.6 g/d. These findings provide new insights into the efficiency of different treatment processes for removing NEOs in current wastewater treatment systems.

A comprehensive evaluation of influencing factors of neonicotinoid insecticides (NEOs) in farmland soils across China: First focus on film mulching

Neonicotinoid insecticide (NEO) residues in agricultural soils have concerning and adverse effects on agroecosystems. Previous studies on the effects of farmland type on NEOs are limited to comparing greenhouses with open fields. On the other hand, both NEOs and microplastics (MPs) are commonly found in agricultural fields, but their co-occurrence characteristics under realistic fields have not been reported. This study grouped farmlands into three types according to the covering degree of the film, collected 391 soil samples in mainland China, and found significant differences in NEO residues in the soils of the three different farmlands, with greenhouse having the highest NEO residue, followed by farmland with film mulching and farmland without film mulching (both open fields). Furthermore, this study found that MPs were significantly and positively correlated with NEOs. As far as we know this is the first report to disclose the association of film mulching and MPs with NEOs under realistic fields. Moreover, multiple linear regression and random forest models were used to comprehensively evaluate the factors influencing NEOs (including climatic, soil, and agricultural indicators). The results indicated that the random forest model was more reliable, with MPs, farmland type, and total nitrogen having higher relative contributions.

Fabrication of Nitrogen Based Magnetic Conjugated Microporous Polymer for Efficient Extraction of Neonicotinoids in Water Samples

Facile and sensitive methods for detecting neonicotinoids (NEOs) in aquatic environments are crucial because they are found in extremely low concentrations in complex matrices. Herein, nitrogen-based magnetic conjugated microporous polymers (Fe3O4@N-CMP) with quaternary ammonium groups were synthesized for efficient magnetic solid-phase extraction (MSPE) of NEOs from tap water, rainwater, and lake water. Fe3O4@N-CMP possessed a suitable specific surface area, extended π-conjugated system, and numerous cationic groups. These properties endow Fe3O4@N-CMP with superior extraction efficiency toward NEOs. The excellent adsorption capacity of Fe3O4@N-CMP toward NEOs was attributed to its π-π stacking, Lewis acid-base, and electrostatic interactions. The proposed MSPE-HPLC-DAD approach based on Fe3O4@N-CMP exhibited a wide linear range (0.1-200 µg/L), low detection limits (0.3-0.5 µg/L), satisfactory precision, and acceptable reproducibility under optimal conditions. In addition, the established method was effectively utilized for the analysis of NEOs in tap water, rainwater, and lake water. Excellent recoveries of NEOs at three spiked levels were in the range of 70.4 to 122.7%, with RSDs less than 10%. This study provides a reliable pretreatment method for monitoring NEOs in environmental water samples.

Neonicotinoid insecticides and metabolites levels in neonatal first urine from southern China: Exploring links to preterm birth

Neonicotinoids (NEOs) have indeed become the most widely used insecticides worldwide. Concerns have been raised about their potential impact on newborns due to maternal exposure and their unique neurotoxic mode of action. However, it is still poorly understood whether in utero exposure of pregnant women to environmental NEOs and their metabolites can cause carryover effects on vulnerable newborns and subsequent health consequences. In this study, we determined the concentrations of 13 NEOs and their metabolites in the first urine collected from 92 newborns, both preterm and full-term, in southern China during 2020 and 2021. NEOs and their metabolites were identified in 91 urine samples, with over 93% of samples containing a cocktail of these compounds, confirming their maternal-fetal transfer. N-desmethyl-acetamiprid, imidaclothiz, clothianidin and flonicamid were the most commonly detected analytes, with detection frequencies of 59-87% and medians of 0.024-0.291 ng/mL in the urine. The relative abundance of imidaclothiz was significantly higher in preterm newborns, those with head circumferences below 33 cm, birth lengths less than 47 cm, and weights below 2500 g (p < 0.05). When comparing newborns in the 2nd quartile of imidaclothiz concentrations with those in the 1st quartile, we observed a significant increase in the odds of preterm outcomes in the unadjusted model (odds ratio = 3.24, 95% confidence interval = 1.02-10.3). These results suggest that exposure to elevated concentrations of imidaclothiz may be associated with preterm birth.

Current-use pesticides monitoring and ecological risk assessment in vegetable soils at the provincial scale

Pesticides represent one of the largest intentional inputs of potentially hazardous compounds into agricultural soils. However, as an important vegetable producing country, surveys on pesticide residues in soils of vegetable production areas are scarce in China. This study presented the occurrence, spatial distribution, correlation between vegetable types and pesticides, and ecological risk evaluation of 94 current-use pesticides in 184 soil samples from vegetable production areas of Zhejiang province (China). The ecological risks of pesticides to soil biota were evaluated with toxicity exposure ratios (TERs) and risk quotient (RQ). The pesticide concentrations varied largely from below the limit of quantification to 20703.06 μg/kg (chlorpyrifos). The situation of pesticide residues in Jiaxing is more serious than in other cities. Soils in the vegetable areas are highly diverse in pesticide combinations. Eisenia fetida suffered exposure risk from multiple pesticides. The risk posed by chlorpyrifos, which exhibited the highest RQs at all scenarios, was worrisome. Only a few pesticides accounted for the overall risk of a city, while the other pesticides make little or zero contribution. This work will guide the appropriate use of pesticides and manage soil ecological risks, achieving green agricultural production.

Ecotoxicological impact of dinotefuran insecticide and its metabolites on non-targets in agroecosystem: Harnessing nanotechnology- and bio-based management strategies to reduce its impact on non-target ecosystems

The class of insecticides known as neonicotinoid insecticides has gained extensive application worldwide. Two characteristics of neonicotinoid pesticides are excellent insecticidal activity and a wide insecticidal spectrum for problematic insects. Neonicotinoid pesticides can also successfully manage pest insects that have developed resistance to other insecticide classes. Due to its powerful insecticidal properties and rapid plant absorption and translocation, dinotefuran, the most recent generation of neonicotinoid insecticides, has been widely used against biting and sucking insects. Dinotefuran has a wide range of potential applications and is often used globally. However, there is growing evidence that they negatively impact the biodiversity of organisms in agricultural settings as well as non-target organisms. The objective of this review is to present an updated summary of current understanding regarding the non-target effects of dinotefuran; we also enumerated nano- and bio-based mitigation and management strategies to reduce the impact of dinotefuran on non-target organisms and to pinpoint knowledge gaps. Finally, future study directions are suggested based on the limitations of the existing studies, with the goal of providing a scientific basis for risk assessment and the prudent use of these insecticides.

Comprehensive effects of thiamethoxam from contaminated soil on lettuce growth and metabolism

The second-generation neonicotinoid thiamethoxam, is prevalent in soils because of its extensive application and persistence. However, the comprehensive effects of thiamethoxam residue in soils on cultivated plants are still poorly understood. This study examined variations of growth state, physiological parameters, antioxidant activity, and metabolites in lettuce after thiamethoxam exposure; the removal effects of different washing procedures were also investigated. The results indicated that thiamethoxam in soils significantly increased the fresh weight, seedling height and chlorophyll content in lettuce, and also altered its lipid, carbohydrate, nucleotide and amino acids composition based on untargeted metabolomics. KEGG pathway analysis uncovered a disruption of lipid pathways in lettuce exposed to both low and high concentrations of thiamethoxam treatments. In addition, the terminal residues of thiamethoxam in lettuce were below the corresponding maximum residue limits stipulated for China. The thiamethoxam removal rates achieved by common washing procedures in lettuce ranged from 26.9% to 42.6%. This study thus promotes the understanding of the potential food safety risk caused by residual thiamethoxam in soils.

Assessing potential soil pollution from plant waste disposal: A modeling analysis of pesticide contamination

Pesticide residues can be taken up by plants after pesticide application, potentially resulting in soil pollution following the disposal of plant wastes at harvest. Currently, there is a lack of simple and efficient methods that can conduct high-throughput simulations to explore this problem across various chemicals and plant species. We present a modeling approach to simulating pesticide residue concentrations in soil as a result of plant waste disposal to assess the impact of plant wastes on agricultural soil pollution with respect to pesticide residues. This modeling approach employs well-established plant uptake models, providing versatility in evaluating different chemicals and plant species. The simulation process was tabulated in the spreadsheet interface, providing users with the flexibility to adjust input values for specific chemicals, plant species, and regions. The simulation results revealed that pesticides with relatively low lipophilicity (i.e., log KOW < 2) had low simulated residue concentrations in the soil as a result of plant waste disposal at harvest, whereas soil concentrations for lipophilic pesticides dramatically rose. This indicated that disposal of plant waste in agricultural soils will not pose significant ecological concerns to pesticides with low lipophilicity. The variability analysis showed that for certain pesticides, environmental factors (such as temperature and humidity) had a significant impact on the simulated residue concentrations in the soil as a result of plant waste disposal, which aided in the assessment of regional ecological risk as well as plant disposal management. Although some modeling aspects such as plant decomposition process, advanced plant uptake models, heterological distribution of residue concentrations in the soil, and plant waste stacking patterns require further research, the proposed approach can be used to assist in managing soil pesticides from plant waste disposal in preliminary stages.

The combined effect of bromadiolone and ivermectin (iBr) in controlling both rodents and their fleas

Rodent pests not only cause severe agricultural loss but also spread zoonotic pathogens to human beings. Anticoagulant rodenticides are widely used to decrease the population densities of rodents but often lead to the spillover of ectoparasites because fleas and ticks may gather on surviving rodents. Therefore, it is necessary to kill fleas and ticks before culling rodents to minimize the risk of pathogen transmission. In this study, we used a mixture of ivermectin (an antiparasitic drug) and bromadiolone (an anticoagulant rodenticide) to control both rodent and flea/tick abundances. We found that in a laboratory test, 0.01% ivermectin bait was not lethal for greater long-tailed hamsters after 7 days of treatment, while 0.1% ivermectin bait was lethal for approximately 33% of treated rodents. In a field test, bait containing 0.001%, 0.005%, 0.01%, and 0.05% ivermectin decreased the number of fleas per vole of Brandt's voles to 0.42, 0.22, 0.12, and 0.2, respectively, compared with 0.77 in the control group, indicating that 0.01% ivermectin bait performed best in removing fleas. In another laboratory test, bait containing a 0.01% ivermectin and 0.005% bromadiolone mixture caused the death of all voles within 6-14 days after the intake of the bait. In the field test, the bait containing 0.01% ivermectin and 0.005% bromadiolone reduced the average number of fleas per vole to 0.35, which was significantly lower than the 0.77 of the control group. Our results indicate that a 0.01% ivermectin and 0.005% bromadiolone mixture could be used to control both rodents and fleas to minimize the spillover risk of disease transmission when using traditional rodenticides.

Present status of insecticide impacts and eco-friendly approaches for remediation-a review

Insecticides are indispensable for modern agriculture to ensuring crop protection and optimal yields. However, their excessive use raises concerns regarding their adverse effects on agriculture and the environment. This study examines the impacts of insecticides on agriculture and proposes remediation strategies. Excessive insecticide application can lead to the development of resistance in target insects, necessitating higher concentrations or stronger chemicals, resulting in increased production costs and disruption of natural pest control mechanisms. In addition, non-target organisms, such as beneficial insects and aquatic life, suffer from the unintended consequences of insecticide use, leading to ecosystem imbalances and potential food chain contamination. To address these issues, integrated pest management (IPM) techniques that combine judicious insecticide use with biological control and cultural practices can reduce reliance on chemicals. Developing and implementing selective insecticides with reduced environmental persistence is crucial. Promoting farmer awareness of responsible insecticide use, offering training and resources, and adopting precision farming technologies can minimize overall insecticide usage.

Distribution characteristics and risk assessment of neonicotinoid insecticides in planting soils of mainland China

Neonicotinoid insecticides (NEOs) are generally used in crop production. Their widespread use on agricultural soil has raised concerns regarding their health and ecological risks. Previous studies have reported the contamination of the farmland soils with NEOs from the coastal provinces of China. Information about NEOs at the national scale as well as the residues of their metabolites are relatively unknown. In this study, 391 soil samples were collected from 31 provinces in nine agricultural regions across mainland China, and the concentrations of ten parent NEOs and three metabolites were determined. At least one NEO was detected in all soil samples, with the sum of the NEOs (ΣNEOs) ranging from 0.04 to 702 μg/kg. The most common parent NEO and metabolite are imidacloprid and imidacloprid-urea, respectively. The concentrations of NEOs in coastal regions at the same latitude were higher than those in inland regions. The NEOs were further compared in the soils of seven types of monocrops and three types of multiple crops (multicrops) (i.e., two types of crops were produced in succession or simultaneously within the decade of this study). The results showed that the highest NEO residues were found in soils planted with vegetables (VE), fruits (FR), and cotton (CO) monocrops and VE & FR multicrops. Differences in NEO concentrations were observed between soils planted with monocrops and multicrops. For example, VE & FR > VE > vegetables and grains (VE & GR) > GR. Moreover, the health risks posed by NEOs in agricultural soils in China are extremely low, and the ecological risks require urgent attention. Particularly, individual NEOs in > 45% of agricultural soils in mainland China may have sublethal effects on two non-target species (HQnon-target > 0.01).

Exploring the toxicity of biodegradable microplastics and imidacloprid to earthworms (Eisenia fetida) from morphological and gut microbial perspectives

Biodegradable microplastics (BMPs) pose serious environmental problems to soil organisms, and their adsorption capacity might make pesticides more dangerous for soil organisms. Therefore, in this study, polylactic acid (PLA) BMPs and imidacloprid (IMI) were used as a representative of BMPs and pesticides, respectively. Eisenia fetida was used as a test animal to investigate the effects of environmentally relevant concentrations of single and compound contaminated PLA BMPs and IMI on mortality, growth, number of offspring, tissue damage, and gut microorganisms of E.fetida. Exposure to PLA BMPs treatment and PLA BMPs + IMI treatment resulted in a sustained increase in E.fetida mortality, reaching 16.7% and 26.7%, respectively. The growth inhibition rate of single treatments was significantly increased. The compound contamination had the greatest effect on E.fetida offspring compared to the control. PLA BMPs and IMI cause histological damage to E.fetida, with the compound treatment causing the most severe damage. Based on the results of 16S sequencing, the bacterial communities in E.fetida gut and soil treated to PLA BMPs and IMI were significantly different. PLA BMPs + IMI treatment suppresses the abundance and diversity of E.fetida gut microorganisms, disrupting the homeostasis of bacterial communities and causing immune and metabolic dysfunction. These findings highlight the more severe damage of combined PLA BMPs and IMI pollution to E.fetida, and help to assess the risk of earthworm exposure to environmentally relevant concentrations of PLA BMPs and IMI.

Occurrence and ecological risks of flonicamid and its metabolites in multiple substrates from intensive rice-vegetable rotations in tropical China

Rice-vegetable rotations are dominant in (sub)-tropical agriculture worldwide. However, fate and risks of the insecticide flonicamid (FLO) and its main degradates (collectively called FLOMs) in multiple substrates from those cropping systems remain largely unknown. In this study, we characterized residual concentrations, driving factors, transport, and potential ecological risks of FLOMs in different substrates in 28 tropical rice-vegetable rotations. Concentrations (median) of FLOMs were 0.013-3.03 (0.42) ng g-1 in plants, 0.012-1.92 (0.23) ng g-1 in soil, 0.029-0.63 (0.126) μg L-1 in water, and 0.002-0.398 (0.055) ng g-1 in sediments. Flonicamid and its metabolite N-(4-trifluoromethylnicotinoyl) glycine were the dominant species in the four substrates (84.1 % to 88.5 %). Plants had the highest levels of FLOMs, with the highest bioconcentration factor in peppers. According to boosted regression trees coupled with a partial least squares structural equation model, levels and composition of FLOMs showed high spatiotemporal and crop-related patterns in different substrates, with patterns highly codetermined by agricultural practices (e.g., crop type and FLO/neonicotinoid/pyrethroid applications), substrate parameters (e.g., pH, organic matter or total organic carbon), and climate features (e.g., wet/dry seasons). Moreover, a fugacity method indicated differences in transport and partitioning patterns in different substrates during rice and vegetable planting periods. Integrated substrate risk assessment of FLOMs contamination was conducted based on species-sensitive distributions and substrate weight index. Although overall risks of FLOM contamination in tropical rice-vegetable rotations were negligible to low, the highest risks were in soils, vegetable planting periods, and a central intensively planted area.

Association between urinary neonicotinoid insecticide levels and dyslipidemia risk: A cross-sectional study in Chinese community-dwelling elderly

Experimental evidence has demonstrated that neonicotinoids (NEOs) exposure can cause lipid accumulation and increased leptin levels. However, the relationship between NEOs exposure and dyslipidemia in humans remains unclear, and the interactive effects of NEOs and their characteristic metabolites on dyslipidemia remain unknown. We detected 14 NEOs and their metabolites in urine samples of 500 individuals (236 and 264 with and without dyslipidemia, respectively) randomly selected from the baseline of the Yinchuan community-dwelling elderly cohort (Ningxia, China). The NEOs and their metabolites were widely detected in urine (87.2-99.6 %) samples, and the median levels ranged within 0.06-0.55 μg/g creatinine. The positive associations and dose-dependent relationships of thiacloprid, imidacloprid-olefin, and imidacloprid-equivalent total with dyslipidemia were validated using restricted cubic spline analysis. Mixture models revealed a positive association between the NEOs mixture and dyslipidemia risk, with urine desnitro-imidacloprid ranked as the top contributor. The Bayesian Kernel Machine Regression models showed that the NEOs mixtures were associated with increased dyslipidemia when the chemical mixtures were ≥ 25th percentile compared to their medians, and desnitro-imidacloprid and imidacloprid-olefin were the major contributors to the combined effect. Given the widespread use of NEOs and the dyslipidemia pandemic, further investigations are urgently needed to confirm our findings and elucidate the underlying mechanisms.

Transport of neonicotinoid insecticides in a wetland ecosystem: Has the cultivation of different crops become the major sources?

Extensive application of neonicotinoid insecticides (NNIs) in agricultural production has resulted in widespread contamination of multiple environmental media. To investigate the occurrence and fate of NNIs in the largest marsh distribution area in Northeast China, an integrated ecosystem covering farmlands, rivers, and marshes, referred to as the farmland-river-marsh continuum in this study, was chosen for soil, water, and sediment sampling. Five NNIs were detected, with imidacloprid (IMI), thiamethoxam (THM), and clothianidin (CLO) being the most frequently detected ones in different samples. Concentrations of target NNIs in soil, surface water, and sediment samples were 2.23-136 ng/g dry weight (dw), 3.20-51.7 ng/L, and 1.53-8.40 ng/g dw, respectively. In soils, NNIs were detected more often and at higher concentrations in upland fields, while the concentration of NNIs in the soybean-growing soils (71.5 ng/g dw) was significantly higher than in the rice-growing soils (18.5 ng/g dw) (p < 0.05). Total concentration of NNIs in surface water was lower in the Qixing River channel than inside the marsh, while that in sediments showed an opposite trend. Total migration mass of IMI from approximately 157,000 ha of farmland soil by surface runoff was estimated to be 2636-3402 kg from the application time to the sampling period. The storage of NNIs in sediments was estimated to range from 45.9 to 252 ng/cm². The estimated environmental risks, calculated as the risk quotients (RQs), revealed low risks to aquatic organisms (RQs <0.1) from the residual concentrations of NNIs in water.

The widespread presence of triazole fungicides in greenhouse soils in Shandong Province, China: A systematic study on human health and ecological risk assessments

Triazole fungicides (TFs) are extensively used on greenhouse vegetables and are ubiquitously detected in the environment. However, the human health and ecological risks associated with the presence of TFs in the soil are unclear. In this study, ten widely used TFs were measured in 283 soil samples from vegetable greenhouses across Shandong Province, China, and their potential human health and ecological risks were assessed. Among all soil samples, difenoconazole, myclobutanil, triadimenol, and tebuconazole were the top detected TFs, with detection rates of 85.2-100%; these TFs had higher residues, with average concentrations of 5.47-23.8 μg/kg. Although most of the detectable TFs were present in low amounts, 99.3% of the samples were contaminated with 2-10 TFs. Human health risk assessment based on hazard quotient (HQ) and hazard index (HI) values indicated that TFs posed negligible non-cancer risks for both adults and children (HQ range, 5.33 × 10-10 to 2.38 × 10-5; HI range, 1.95 × 10-9 to 3.05 × 10-5, <1). Ecological risk assessment based on the toxicity exposure ratio (TER) and risk quotient (RQ) values indicated that difenoconazole was a potential risk factor for soil organisms (TERmax = 1 for Eisenia foetida, <5; RQmean = 1.19 and RQmax = 9.04, >1). Moreover, 84 of the 283 sites showed a high risk (RQsite range, 1.09-9.08, >1), and difenoconazole was the primary contributor to the overall risk. Considering their ubiquity and potential hazards, TFs should be continuously assessed and prioritized for pesticide risk management.

The distribution and human health risk assessment of eight neonicotinoid residues in agricultural soils from four provinces, south China

The widespread use of neonicotinoid (neonic) insecticides in China's agricultural sector has led to high residual concentrations in the agroecosystem. Since soil is the primary source of direct pesticide exposure, soil contamination is a significant concern, particularly in regions with extensive agricultural production. This study aims to determine the spatial distribution of neonics in farmlands from four southern provinces that are home to China's crucial commercial grain bases. By combining eight neonics into imidacloprid-equivalent total neonics (IMI_RPF) using the relative potency factor method, the ecological risks to humans were also assessed. The results showed that imidacloprid had the highest detection rate (96%-100%), followed by thiamethoxam and clothianidin, which ranged from 44% to 64%. Maximum and average IMI_RPF values in soil samples from Zhejiang Province were 277.02 and 46.05 μg kg^-1 (dry weight), respectively. Guangdong (maximum = 191.62 μg kg^-1, mean = 39.70 μg kg^-1) and Jiangxi (maximum = 199.13 μg kg^-1, mean = 28.95 μg kg^-1) had comparable IMI_RPF while Jiangsu had the lowest level of total neonics, with a maximum of 86.07 μg kg^-1 and a mean of 19.49 μg kg^-1. A significant positive correlation between IMI_RPF and total organic carbon in soils was also found. The average daily doses of neonics from soil-borne exposure through food intake, soil ingestion, inhalation, and dermal contact calculated for adults and children in each province were all lower than the reference dose (RfD, 57 μg kg^-1 d^-1) of imidacloprid. However, the potential health risk to human health cannot be disregarded, given their increasing use and pervasiveness in the environment. Our results help to raise concerns about the safety of the agroecological environment under neonic exposure in the major agricultural provinces of southern China.

Integrate transcriptomic and metabolomic analysis reveals the underlying mechanisms of behavioral disorders in zebrafish (Danio rerio) induced by imidacloprid

Imidacloprid, a widely used neonicotinoid insecticide, poses a significant threat to aquatic ecosystems. Behavior is a functional indicator of the net sensory, motor, and integrative processes of the nervous system and is presumed to be more sensitive in detecting toxicity. In the present study, we investigated the behavioral effects of imidacloprid at the level of environmental concentrations (1, 10 and 100 μg/L) for a constant exposure to zebrafish adults, and performed the integrated transcriptomic and metabolomic analysis to analyze the molecular mechanism underlying behavioral effects of imidacloprid. Our results show that imidacloprid exposure significantly induce behavioral disruptions characterized by anxiety, depression, and reduced physiological function including exploratory, decision, social interaction and locomotor activity. Integrated transcriptomic and metabolomic analysis indicate that the disruption of circadian rhythm, metabolic imbalance of arginine and proline, and neurotransmitter disorder are the underlying molecular mechanisms of behavioral impairment induced by imidacloprid. The "gene-metabolite-disease" network consisted by 11 metabolites and 15 genes is associated human disease Alzheimer's disease (AD) and schizophrenia. Our results confirm the behavioral impairment induced by imidacloprid at environmental concentrations for constant exposure. The identified genes and metabolites can be used not only to illustrate the underlying mechanisms, but also can be developed as biomarkers in determining the ecological risk of imidacloprid to aquatic organisms even Homo sapiens.

Oxidative stress and gene expression induced by biodegradable microplastics and imidacloprid in earthworms (Eisenia fetida) at environmentally relevant concentrations

The environmental issues caused by biodegradable microplastics (BMPs) from polylactic acid (PLA) as well as pesticides are of increasing concern nowadays. In this study, the toxicological effects of the single and combined exposure of PLA BMPs and imidacloprid (IMI), a neonicotinoid insecticide, on earthworms (Eisenia fetida) were investigated in terms of oxidative stress, DNA damage, and gene expression, respectively. The results showed that compared with the control, SOD, CAT and AChE activities in the single and combined treatments decreased significantly, and POD activity showed an "inhibition-activation" trend. SOD and CAT activities of combined treatments on day 28 and AChE activity of combined treatment on day 21 were significantly higher than those of the single treatments. For the rest of the exposure period, SOD, CAT and AChE activities in the combined treatments were lower than those in the single treatments. POD activity in the combined treatment was significantly lower than those of single treatments at day 7 and higher than that of single treatments at day 28. MDA content showed an "inhibition-activation-inhibition" trend, and the ROS level and 8-OHdG content increased significantly in both the single and combined treatments. This shows that both single and combined treatments led to oxidative stress and DNA damage. ANN and HSP70 were expressed abnormally, while the SOD and CAT mRNA expression changes were generally consistent with the corresponding enzyme activities. The integrated biomarker response (IBR) values were higher under combined exposures than single exposures at both biochemical and molecular levels, indicating that combined treatment exacerbated the toxicity. However, the IBR value of the combined treatment decreased consistently at the time axis. Overall, our results suggest that PLA BMPs and IMI induce oxidative stress and gene expression in earthworms at environmentally relevant concentrations, thereby increasing the risk of earthworms.

A Modeling Approach for Assessing Ecological Risks of Neonicotinoid Insecticides from Emission to Nontarget Organisms: A Case Study of Cotton Plant

The use of neonicotinoid insecticides in agriculture has posed threats to ecological systems, and there is a need to assess the ecological risks of neonicotinoids from emission to nontarget organisms. We introduced a modeling approach to assess the ecological risks of neonicotinoids using honeybee and earthworm as model organisms, and the simulation was flexible under different environmental conditions. Using the cotton plant as an example, the simulation results demonstrated that under current recommended application rates, the use of common neonicotinoid insecticides posed no threat to earthworms, with the simulated risk quotients (RQs) much lower than 1. However, the simulation for some neonicotinoid insecticides (e.g., acetamiprid) indicated that using these insecticides on cotton plants could threaten honeybees, with simulated RQs higher than 1. The variability analysis showed that in high-latitude regions, the unacceptable risk to honeybees posed by insecticide application can be further elevated due to cold, wet weather that results in relatively high insecticide levels in pollen and nectar. The model evaluation showed large overlaps of simulated risk intervals between the proposed and existing (BeeREX) models. Because the proposed and existing models have different simulation mechanisms, we recommend that these two models be used together to complement each other in future studies. Environ Toxicol Chem 2023;42:928-938. © 2023 SETAC.

Individual and combined toxicity of imidacloprid and two seed dressing insecticides on collembolans Folsomia candida

The aim of this study was to examine the chronic toxicity of imidacloprid (IMI), clothianidin (CLO) and fipronil (FIP) as a single exposure, as well as binary mixtures of IMI with CLO or FIP toward collembolans Folsomia candida, which are fauna present in the soil. Chronic toxicity assays were performed following an ISO guideline in a Tropical Artificial Soil (TAS), and the influence on the number and growth of the juveniles produced were determined. The range of nominal concentrations used in the tests with the individual compounds was 0.08-1.28 mg/kg (IMI), 0.079-1.264 mg/kg (FIP) and 0.007-0.112 mg/kg (CLO), whereas the mixture assays were performed with half the value used in the tests with individual compounds. Based upon single exposures, IMI produced a similar impact of reducing reproduction by 50% (EC₅₀ ranging from 0.74 to 0.85 mg/kg) compared to FIP (EC₅₀ = 0.78 mg/kg), whereas CLO was the most toxic to F. candida (EC₅₀ = 0.08 mg/kg). Their mixtures generally resulted in a diminished effect on reproduction, as evidenced by the higher EC₅₀ values. In contrast, in the case of the IMI+FIP combination at high concentrations at the EC₅₀ level, a synergistic effect on toxicity was observed. The single exposure to the three insecticides and the mixture of IMI-FIP also decreased the size of generated juveniles, which was evidenced by the reduction in the proportion of large juveniles and increased proportion of small juveniles. However, both binary mixtures (IMI-FIP and IMI-CLO) presented antagonistic effects as evidenced by less than expected reductions in growth. Data on the toxic effects of IMI in a mixture with other seed dressing insecticides to collembolans provides useful information to environmental risk assessors by diminishing the uncertainties on the ecological risk of exposure to pesticides, enabling soil management degradation by utilizing multiple insecticides.

Transcriptomics and Metabolomics for Co-Exposure to a Cocktail of Neonicotinoids and the Synergist Piperonyl Butoxide

Here, the transcriptomics and metabolomics on a model of exposure to a cocktail of neonicotinoids (Neo) containing seven commercial compounds and a synergist piperonyl butoxide (PBO) were established. The results showed that Neo and PBO disrupted mRNA and metabolite levels in a dose-dependent manner. Neo caused tryptophan pathway-related neurotoxicity, reduced lipolysis, and promoted fat mass accumulation in the liver, while PBO induced an increase in inflammatory factors and damage to intercellular membranes. Co-exposure enhanced Neo-induced liver steatosis, focal necrosis, and oxidative stress by inhibiting oxidative phosphorylation (OXPHOS). Furthermore, diglycerides and metabolic biomarkers demonstrated that the activation of insulin signaling is associated with restricted OXPHOS, which commonly leads to a high risk of non-alcoholic fatty liver disease (NAFLD) and Alzheimer's disease (AD) as the result of over-synthesis of lipids, low energy supply, and high thermogenesis. The study demonstrates that chronic disease can be induced by Neo and the synergist PBO at the molecular level.

Organophosphate Pesticides and Pyrethroids in Farmland of the Pearl River Delta, China: Regional Residue, Distributions and Risks

A regional-scale survey was conducted to assess the occurrence, distribution, and risk of two extensively used pesticides (organophosphate pesticides and pyrethroids) in agricultural soils from the Pearl River Delta (PRD), South China. All target organophosphate pesticides (OPPs) and pyrethroids (PYs) were detected in the soil samples and both with a detection rate of 100%. The residues of the sum of six OPPs and the sum of four PYs were in the range of LOD-991 ng/g and 8.76-2810 ng/g, respectively. Dimethoate was the dominant OPPs, and fenpropathrin was the predominant PYs in the soils of the PRD region. With intensive agricultural activities, higher residues of OPPs and PYs in soils were detected closer to the seaside, among which Zhuhai city and Huizhou city suffered more serious combined pesticide pollution. The vertical compositional profiles showed that dimethoate could be detected through each soil layer in the PRD region's nine cities. The human exposure estimation of OPPs showed insignificant risks to the local population. In contrast, cypermethrin and fenpropathrin showed a potential ecological risk of 2.5% and 3.75% of the sampling sites, respectively. These results can facilitate those commonly used pesticide controls and promote sustainable soil management.

Influence of temperature and soil moisture on the toxic potential of clothianidin to collembolan Folsomia candida in a tropical field soil

Climate change can alter the toxic effects of pesticides on soil invertebrates. However, the nature and magnitude of the influence of climatic factors on clothianidin impacts in tropical soils are still unknown. The influence of increasing atmospheric temperature and the reduction in soil moisture on the toxicity and risk of clothianidin (seed dressing formulation Inside FS^®) were assessed through chronic toxicity tests with collembolans Folsomia candida in a tropical field soil (Entisol). The risk of clothianidin for collembolans was estimated using the Toxicity-Exposure Ratio (TER) approach. Organisms were exposed to increasing clothianidin concentrations at 20, 25 and 27 °C in combination with two soil moisture conditions (30 and 60% of the maximum water holding capacity-WHC). The effect of temperature and soil moisture content on clothianidin toxicity was verified through the number of F. candida juveniles generated after 28 days of exposure to the spiked soil. The toxicities estimated at 25 °C (EC₅₀__30%WHC = 0.014 mg kg^-1; EC_{50_60%WHC} = 0.010 mg kg^-1) and 27 °C (EC_{50_30%WHC} = 0.006 mg kg^-1; EC_{50_60%WHC} = 0.007 mg kg^-1) were 2.9-3.0-fold (25 °C) and 4.3-6.7-fold (27 °C) higher than those found at 20 °C (EC_{50_30%WHC} = 0.040 mg kg^-1; EC_{50_60%WHC} = 0.030 mg kg^-1), indicating that clothianidin toxicity increases with temperature. No clear influence of soil moisture content on clothianidin toxicity could be observed once the EC₅₀ values estimated at 30% and 60% WHC, within the same temperature, did not significantly differ. A significant risk was detected in all temperatures and soil moisture scenarios studied, and the TER values indicate that the risk can increase with increasing temperatures. Our results revealed that temperature could overlap with soil moisture in regulating clothianidin toxicity and reinforce the importance of including climatic factors in the prospective risk assessment of pesticides.

Occurrence, distribution, and driving factors of current-use pesticides in commonly cultivated crops and their potential risks to non-target organisms: A case study in Hainan, China

Multiple pesticides are heavily applied in crops grown in China's tropics due to the prevalence of diseases and pests, thus posing potential risks to nontarget organisms (e.g., honeybees, lacewings, ladybugs, and humans). However, there is little information on this topic. This study is the first assessment of the occurrence, driving factors, and ecological/human health risks of 32 current-use pesticides (CUPs) in 10 frequently-planted crops collected from practicing rice-vegetable rotation systems in Hainan, China. Of the 132 whole crop samples, 44 (33.3 %) residues from ≥8 pesticides were detected in 9.09 % of crop samples with concentrations ≥0.5 mg kg-1. Six pesticide residues, namely carbendazim, pyraclostrobin, acetamiprid, thiophanate methyl, phoxim, and imidacloprid, were detected in 72.7 % of samples, with concentrations ranging from 0.0021 to 13.5 (median = 0.032) mg kg-1. Among them, carbendazim, pyraclostrobin, and acetamiprid were the most common, contributions from 10.2 to 25.5 % and a detection frequency ranging from 25.6 to 56.1 %. The order of total concentration of 32 CUPs (∑32 CUP) concentrations during the year was January > May > November > August and vegetables > rice, being highly related with pesticides usage pattern, crop type, plant accumulation/dissipation and plant lipid contents. The ecological risk quotients (RQs) to four beneficial terrestrial organisms showed that 9.6-39.1 % of samples posed a potential medium or high ecological risk, with 13.6-65.9 % of samples at ∑RQ > 1 being highly affected by the residues of neonicotinoids and emamectin benzoate. Emamectin benzoate (8.9 %) and acetamiprid (5.6 %) exceeded the individual Maximum Residue Levels based on Chinese legislation (GB2763-2021). Moreover, cumulative dietary exposure presented a higher risk to humans in 11.0 and 22.0 % of the cases for acute and chronic, mainly originating from the higher concentration contributors of systemic pesticides in edible crops. Therefore, the regulation and monitoring of CUP residues is imperative for rice-vegetable rotation systems in tropical China to avoid negative effects on nontarget organisms.

Response of microbial community to the remediation of neonicotinoid insecticide imidacloprid contaminated wetland soil by Phanerochaete chrysosporium

Imidacloprid (IMI), a typic neonicotinoid insecticide, is widely used and persist in soils with long half-time causing serious threat to ecosystem and human health. It is urgent to develop suitable and effective methods to accelerate it degradation and alleviate its negative impacts in soil. In this study, the introduction of functional microbe white-rot fungus Phanerochaete chrysosporium to remediate IMI contaminated wetland soil was carried out. The remediation performance and the response of the soil microbial community were examined. The results showed that P. chrysosporium could improve the degradation of IMI in soil no matter the soil was sterilized or not. The bioaugmentation was especially observed in non-sterilized soil under the inoculation patterns of FE and SP with the maximum IMI degradation rate of 91% and 93% in 7 days, respectively. The invertase activity in soil was also enhanced with P. chrysosporium inoculation. Microbial community analysis revealed that P. chrysosporium inoculation could increase the diversity and richness of bacterial community, and stimulate some IMI degraders genera including Ochrobactrum, Leifsonia, Achromobacter, and Bacillus. Moreover, the xenobiotic degradation and metabolism pathway was generally enhanced with P. chrysosporium inoculation based on PICRUSt analysis. These obtained results demonstrated that the introduction of white-rot fungus is of great potentially enabling the remediation of neonicotinoids contaminated soil.

Neonicotinoid Insecticides and Their Metabolites Can Pass through the Human Placenta Unimpeded

Studies on neonicotinoid (NEO) exposure in pregnant women and fetuses are scarce, and transplacental transfer of these insecticides is unknown. In this study, parent NEOs (p-NEOs) and their metabolites (m-NEOs) were determined in 95 paired maternal (MS) and cord serum (CS) samples collected in southern China. Imidacloprid was the predominant p-NEO in both CS and MS samples, found at median concentrations of 1.84 and 0.79 ng/mL, respectively, whereas N-desmethyl-acetamiprid was the most abundant m-NEO in CS (median: 0.083 ng/mL) and MS (0.13 ng/mL). The median transplacental transfer efficiencies (TTEs) of p-NEOs and m-NEOs were high, ranging from 0.81 (thiamethoxam, THM) to 1.61 (olefin-imidacloprid, of-IMI), indicating efficient placental transfer of these insecticides. Moreover, transplacental transport of NEOs appears to be passive and structure-dependent: cyanoamidine NEOs such as acetamiprid and thiacloprid had higher TTE values than the nitroguanidine NEOs, namely, clothianidin and THM. Multilinear regression analysis revealed that the concentrations of several NEOs in MS were associated significantly with hematological parameters related to hepatotoxicity and renal toxicity. To our knowledge, this is the first analysis of the occurrence and distribution of NEOs in paired maternal-fetal serum samples.

Neonicotinoid insecticides promote breast cancer progression via G protein-coupled estrogen receptor: In vivo, in vitro and in silico studies

Neonicotinoid insecticides (NIs) have been widely detected in environmental media and human body with concentrations reaching hundreds of nanomolar to micromolar levels. However, the information about their human health toxicology and mechanism is deficient. Previous studies have implied that NIs might exert estrogenic disruption and promote breast cancer progression, but the molecular mechanism is unclear, especially the molecular initiating event. G protein-coupled estrogen receptor (GPER), as a candidate therapeutic target, plays vital roles in the development of breast cancer. This work aimed to reveal the potential mechanism through GPER pathway. Firstly, we screened the activities of seven most common NIs on GPER signal pathway by calcium mobilization assay. Clothianidin, acetamiprid (ACE), and dinotefuran activated GPER most potently and ACE displayed the highest agonistic activity with the lowest observed effective concentration (LOEC) of 1 μM. The molecular docking and dynamics simulation showed favored interaction trend between the NIs and GPER. The three NIs with GPER activity induced 4T1 breast cancer cells migration and ACE showed the highest potency with LOEC of 100 nM. ACE also induced 4T1 cells proliferation at high concentration of 50 μM and up-regulated GPER expression in a dose-dependent manner. We speculated that both the induction effects of ACE on 4T1 cells proliferation and migration might be owing to the activation and up-regulation of GPER. By using 4T1-Luc cells injected orthotopic tumor model, we found that ACE also promoted in-situ breast cancer growth and lung metastasis in normal mouse dependent on GPER. However, ACE only promoted in-situ breast cancer growth through GPER but not lung metastasis in ovariectomized mice, implying that the ACE-induced lung metastasis should be related to endogenous estrogen from ovary. Overall, we demonstrated that NIs promoted breast cancer progression via GPER pathway at human related exposure levels and their female health risks need urgent concerns.

Differential effects of thiamethoxam and clothianidin exposure on their tissue distribution and chronic toxicity in mice

The frequent application of second-generation neonicotinoids thiamethoxam (TMX) and clothianidin (CLO) has led to a high detectable rate in environment samples and poses threats to nontarget organisms and human beings, however, the information on the influences of long-term exposure at low doses was limited. In this study, the tissue distribution of TMX and CLO in mice at acceptable daily intake (ADI) level and 5 × ADI was determined and the health effects were assessed. TMX and CLO were detected in the liver, serum, lung, heart and kidney in the TMX exposure groups, which indicated that TMX degraded to CLO in mice. Residue levels of TMX in tissues increased with the increasing of doses. The concentrations of CLO in different tissues in the CLO exposure groups were in the order C_kidney > C_lung > C_heart > C_liver. Measurement of biochemical indicators, combined with metabolomic analysis of liver, kidney, and cecal contents, examination of changes in the gut microbiota, and histopathological assessment indicated that both TMX and CLO affected energy absorption and lipid metabolism in mice and destroyed tissue structures. Furthermore, we found that CLO had a stronger effect on metabolism in mice, despite its lower acute toxicity. These results have prompted us to consider the chronic toxicity and potential hazards of chemicals in future risk assessments.

A review of spatiotemporal patterns of neonicotinoid insecticides in water, sediment, and soil across China

Neonicotinoid insecticides (NNIs) have been widely used to control insect pests, while their environmental residues and associated hazardous impacts on human and ecosystem health have attracted increasing attention worldwide. In this study, we examined the current levels and associated spatial and temporal patterns of NNIs in multiple environmental media across China. Concentrations of NNIs in surface water, sediment, and soil were in the range of 9.94-755 ng·L^-1, 0.07-8.30 ng·g^-1 DW, and 0.009-356 ng·g^-1 DW, respectively. The high levels of NNIs in surface water, such as in Yangtze River (755 ng·L^-1), North River (539 ng·L^-1), Nandu River (519 ng·L^-1), and Minjiang River (514 ng·L^-1), were dominated by imidacloprid, thiamethoxam, and acetamiprid due to their extensive use. The levels of NNIs in sediments were relatively low, and the highest concentration (8.30 ng·g^-1 DW) was observed in Dongguan ditch. Sediment-water exchange calculated from fugacity fraction indicated that NNIs in sediment can be released back into the water due to their high solubility and low K_OW. Soils from agricultural zones contained the largest residual NNIs, with imidacloprid concentrations in cultivated soil reaching 119 ng·g^-1 DW. The calculated leaching potential showed that clothianidin has the highest migration potential to deep soil or groundwater. The monitored data of NNIs presented a decreasing trend from 2016 to 2018, which might be caused by the implementation of relevant control policies for NNI applications. The high levels of NNIs mainly occurred in southern China due to frequent agricultural activities and warm and humid meteorological conditions. The results from this study improve our understanding of the pollution levels and environmental behavior of NNIs in different environmental media across China and provide new knowledge that is needed for making future control policies for NNIs production and application.

Efficient degradation of imidacloprid in soil by thermally activated persulfate process: Performance, kinetics, and mechanisms

Imidacloprid (IMI) as a first-generation commercial neonicotinoid has been frequently detected in the environment in recent years. In this study, the efficient degradation of IMI in soil by a thermally activated persulfate (PS) process was investigated. The degradation efficiencies of IMI were in the range of 82-97% with the PS dosage of 10 mM, when the initial concentrations of IMI were 5-50 mg/kg in the soil. Degradation of the IMI was fitted with a pseudo-first-order kinetic model under different reaction temperatures. Inhibition effects of the common inorganic anions on the IMI degradation in the system followed the order Cl^- > HCO₃^- > H₂PO₄^- > NO₃^-. Soil pH and soil organic matter were also main factors affecting the degradation of IMI. The degradation efficiencies (64-97%) of three other typical neonicotinoids (acetamiprid, clothianidin, and dinotefuran) indicated that the thermally activated persulfate process could be used for remediation of neonicotinoid-contaminated soil. Quenching experiments indicated that the major reactive species in IMI degradation were SO₄^•-, O₂^•-, and •OH. Six degradation intermediates of IMI were inferred in the soil, and degradation pathways of IMI included hydroxylation, denitrification, C-N bond break and further oxidation.

Nanocarrier-Loaded Imidaclothiz Promotes Plant Uptake and Decreases Pesticide Residue

There is a great demand for improving the effective utilization of pesticides and reducing their application for sustainable agriculture, and polymeric nanoparticles have provided strong technical support for the efficient delivery of pesticides. To this context, we tried to construct a relatively safe imidaclothiz nano-delivery system for enhanced plant uptake, reduced pesticide residue and improved bioactivity toward green peach aphids. The imidaclothiz could be assembled with the hydrophobic core of SPc through hydrophobic association, which led to the self-assembly of nanoscale imidaclothiz/SPc complex consisting of nearly spherical particles. The SPc decreased the contact angle of imidaclothiz drops and remarkably increased the plant uptake. Furthermore, the bioactivity and control efficacy of imidaclothiz were significantly improved with the help of SPc in both laboratory and field. Excitingly, the residue of imidaclothiz decreased with the help of SPc 7 d after the treatment due to the faster degradation of nanoscale imidaclothiz/SPc complex, which exhibited no negative effects on agronomic traits of tobacco plants. The current study successfully constructed a nano-delivery system for imidaclothiz, which can not only increase the effective utilization of pesticides, but also decrease the pesticide residue.

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.

Synthesis of natural proanthocyanidin based novel magnetic nanoporous organic polymer as advanced sorbent for neonicotinoid insecticides

In this work, a natural proanthocyanidin (PA) based magnetic nanoporous organic polymer (named as PA-MOP) was successfully synthesized for the first time. The PA-MOP possessed high hydrophilic-surface, good magnetic responsiveness and high affinity for neonicotinoid insecticides. It was applied as an advanced magnetic sorbent for extraction of four neonicotinoids (thiamethoxam, imidacloprid, acetamiprid and thiacloprid) from environmental water, peach juice and honey samples prior to HPLC analysis. Under optimal conditions, the limits of detection for the analytes at S/N = 3 were 0.02-0.08 ng mL^-1 for water, 0.03-0.10 ng mL^-1 for peach juice and 0.05-0.16 ng g^-1 for honey sample. The method recoveries were 80.0%-114.8%, with the relative standard deviations below 6.8%. The values of matrix effect were from -1.5% to -9.3%. Based on theory calculation, the extraction mechanism can be attributed to multiple interactions between the PA-MOP and the neonicotinoids, in which hydrogen bonding, π-π stacking and electrostatic interactions are the major interactions.

Pollution status, influencing factors and environmental risks of neonicotinoids, fipronil and its metabolites in a typical semi-closed bay in China

The occurrence, spatiotemporal variations, influence factors and environmental risks of eight common neonicotinoids (NEOs), fipronil, and three fipronil metabolites (fipronil and its metabolites are collectively referred to as FIPs) in different seasons from the estuary to the inner area of Jiaozhou Bay, China were comprehensively investigated. First- and second-generation NEOs were found to be the predominant pesticides in this area. The average contents of ∑NEOs and ∑FIPs from the estuary to the inner bay decreased from 12.99 ng/L to 0.82 ng/L and from 1.10 ng/L to 0.17 ng/L, respectively. NEO and FIP concentrations were higher in summer and autumn. High ∑NEO content is distributed in main inflow rivers, such as Dagu River and Licun River, which are influenced by pesticide application. NEO concentrations in all rivers were high upstream and low downstream because of the influence of heavy rainfall and seawater dilution in summer. NEO concentrations were high along the coast and low at the mouth and center of Jiaozhou Bay in summer and autumn and evenly distributed in winter and spring. Temperature has a great influence on most NEOs and FIPs owing to its effect on their degradation. Nitrogen-containing nutrients have an important influence on the distribution of fipronil and acetamiprid, which may be due to the activity of nitrogen-containing functional groups in their structure. Only Licun River, Dagu River and Haibo river sewage treatment plant in summer posed a certain risk of chronic toxicity for NEOs using the new threshold established by the species sensitive distribution (SSD) method for Chinese native aquatic lives. These findings should arouse people's attention.

Effects of Urbanization on Landscape Patterns in the Middle Reaches of the Yangtze River Region

The middle reaches of the Yangtze River region (MRYRR) are China’s first trans-regional urban agglomeration, located in the center of the Yangtze River Economic Belt. The MRYRR is an important ecological reserve, and its land cover changes are affected by both socio-economic development and geographical environment. In this paper, Landsat ETM/TM/OLI remote sensing images were used to monitor land use and landscape patterns from 1990 to 2015. Through supervised classification, land use transfer matrix, landscape pattern metrics and correlation analysis, the spatial-temporal patterns of land use change and its relationship with socio-economic in the study area were revealed. The results showed that: (1) the main land use types in the study area were cropland (CL) and forestland (FL), accounting for more than three-quarters of the study area. During the study period, built-up land (BL) increased, CL decreased, FL increased first and then decreased; (2) the BL expanded mainly by occupying CL and FL, and regional landscape pattern was gradually fragmented, with complex patch shape and increasing diversity and heterogeneity. Among them, the BL is gradually gathered, and the FL and CL are gradually fragmented; (3) in the past 25 years, the urbanization process in this region has been obvious, and the Gross Domestic Product (GDP) has increased by 36 times. The socioeconomic variables were positively correlated with BL, orchard (OL) and Shannon diversity index (SHID), and negatively correlated with CL, Wasteland (WL), mean patch size (MPS) and contagion size (CONTAG). The results showed that the urbanization development has a great impact on the region, and the ecological protection task is still challenging. It is necessary to protect high-quality cropland and draw a red line for ecological protection. We should strengthen the construction of ecological corridors and ecological nodes to adapt to regional sustainable development.