Longitudinal, Seasonal, and Occupational Trends of Multiple Pesticides in House Dust

Associations between neonicotinoids and liver function measures in US adults: National Health and Nutrition Examination Survey 2015-2016

Background

Toxicological studies indicate that neonicotinoids may be associated with disruptions in liver function due to an increase in oxidative stress. There are scant epidemiological studies investigating the chronic hepatotoxic effects of neonicotinoids.

Objective

To examine the association between detectable concentrations of parent neonicotinoids and neonicotinoid metabolites with liver function markers among US adults, and whether sex modifies this association.

Methods

National Health and Nutrition Examination Survey 2015-2016 data were used to estimate associations between detectable neonicotinoids and serum alkaline phosphatase (ALP), alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transaminase (GGT), albumin, total bilirubin, total protein, and Hepatic Steatosis Index (HSI) using multiple linear regression.

Results

Detectable levels of N-desmethyl-acetamiprid were associated with a decrease in GGT (β = -3.54 unit/l; 95% confidence interval [CI] = -6.48, -0.61) and detectable levels of 5-hydroxy-imidacloprid were associated with a decrease in HSI (β = -1.11; 95% CI = -2.14, -0.07). Sex modified the association between any parent neonicotinoid and ALP (Pint = 0.064) and the association between clothianidin and ALP (Pint = 0.019), with a pattern of positive associations in males and inverse associations in females, though stratified associations did not reach statistical significance. Sex also modified the association between 5-hydroxy-imidacloprid and total protein (Pint = 0.062), with a significant positive association in females (β = 0.14 g/dl; 95% CI = 0.03, 0.25) and a null association in males.

Conclusion

Detectable concentrations of neonicotinoid metabolites were inversely associated with GGT and HSI in US adults. Evidence suggests neonicotinoids may influence liver function differently depending on sex. Future research is recommended to replicate the findings as the study was limited in its cross-sectional nature and inability to examine continuous neonicotinoid concentrations with liver function.

Occurrence of pesticide residues in indoor dust of farmworker households across Europe and Argentina

Pesticides are widely used as plant protection products (PPPs) in farming systems to preserve crops against pests, weeds, and fungal diseases. Indoor dust can act as a chemical repository revealing occurrence of pesticides in the indoor environment at the time of sampling and the (recent) past. This in turn provides information on the exposure of humans to pesticides in their homes. In the present study, part of the Horizon 2020 funded SPRINT project, the presence of 198 pesticide residues was assessed in 128 indoor dust samples from both conventional and organic farmworker households across Europe, and in Argentina. Mixtures of pesticide residues were found in all dust samples (25-121, min-max; 75, median). Concentrations varied in a wide range (<0.01 ng/g-206 μg/g), with glyphosate and its degradation product AMPA, permethrin, cypermethrin and piperonyl butoxide found in highest levels. Regarding the type of pesticides, insecticides showed significantly higher levels than herbicides and fungicides. Indoor dust samples related to organic farms showed a significantly lower number of residues, total and individual concentrations than those related to conventional farms. Some pesticides found in indoor dust were no longer approved ones (29 %), with acute/chronic hazards to human health (32 %) and with environmental toxicity (21 %).

Characterization of Environmental Levels of Pesticide Residues in Household Air and Dust Samples near a Bioenergy Plant Using Treated Seed as Feedstock

Exposure to neonicotinoid insecticides is associated with adverse human health outcomes. There is environmental contamination in Saunders County, Nebraska, due to the accumulation of fungicides and insecticides from a now-closed ethanol plant using seed corn as stock. A pilot study quantified environmental contamination in nearby houses from residual pesticides by measuring dust and air (indoor/outdoor) concentrations of neonicotinoids and fungicides at the study site (households within two miles of the plant) and control towns (20-30 miles away). Air (SASS® 2300 Wetted-Wall Air Sampler) and surface dust (GHOST wipes with 4 × 4-inch template) samples were collected from eleven study households and six controls. Targeted analysis quantified 13 neonicotinoids, their transformation products and seven fungicides. Sample extracts were concentrated using solid phase extraction (SPE) cartridges, eluted with methanol and evaporated. Residues were re-dissolved in methanol-water (1:4) prior to analysis, with an Acquity H-Class ultraperformance liquid chromatograph (UPLC) and a Xevo triple quadrupole mass spectrometer. We compared differences across chemicals in air and surface dust samples at the study and control sites by dichotomizing concentrations above or below the detection limit, using Fisher's exact test. A relatively higher detection frequency was observed for clothianidin and thiamethoxam at the study site for the surface dust samples, similarly for thiamethoxam in the air samples. Our results suggest airborne contamination (neonicotinoids and fungicides) from the ethanol facility at houses near the pesticide contamination.

Neonicotinoid insecticides and their metabolites: Specimens tested, analytical methods and exposure characteristics in humans

The use of neonicotinoid insecticides (NEOs) has been rising globally due to their broad-spectrum insecticidal activity, unique mode of neurotoxic action and presumed low mammalian toxicity. Given their growing ubiquity in the environment and neurological toxicity to non-target mammals, human exposure to NEOs is flourishing and now becomes a big issue. In the present work, we demonstrated that 20 NEOs and their metabolites have been reported in different human specimens with urine, blood and hair as the dominance. Sample pretreatment techniques of solid-phase and liquid-liquid extractions coupled with high performance liquid chromatography-tandem mass spectrometry have successfully achieved matrix elimination and accurate analysis. We also discussed and compared exposure characteristics of these compounds among types of specimens and different regions. A number of important knowledge gaps were also identified in order to further facilitate the understanding of health effects of NEO insecticides, which include, but are not limited to, identification and use of neuro-related human biological samples for better elucidating neurotoxic action of NEO insecticides, adoption of advanced non-target screening analysis for a whole picture in human exposure, and expanding investigations to cover non-explored but NEO-used regions and vulnerable populations.

Alteration of oral microbiome composition in children living with pesticide-exposed farm workers

Our prior work shows that azinphos-methyl pesticide exposure is associated with altered oral microbiomes in exposed farmworkers. Here we extend this analysis to show the same association pattern is also evident in their children. Oral buccal swab samples were analyzed at two time points, the apple thinning season in spring-summer 2005 for 78 children and 101 adults and the non-spray season in winter 2006 for 62 children and 82 adults. The pesticide exposure for the children were defined by the farmworker occupation of the cohabitating household adult and the blood azinphos-methyl detection of the cohabitating adult. Oral buccal swab 16S rRNA sequencing determined taxonomic microbiota proportional composition from concurrent samples from both adults and children. Analysis of the identified bacteria showed significant proportional changes for 12 of 23 common oral microbiome genera in association with azinphos-methyl detection and farmworker occupation. The most common significantly altered genera had reductions in the abundance of Streptococcus, suggesting an anti-microbial effect of the pesticide. Principal component analysis of the microbiome identified two primary clusters, with association of principal component 1 to azinphos-methyl blood detection and farmworker occupational status of the household. The children's buccal microbiota composition clustered with their household adult in ∼95% of the households. Household adult farmworker occupation and household pesticide exposure is associated with significant alterations in their children's oral microbiome composition. This suggests that parental occupational exposure and pesticide take-home exposure pathways elicit alteration of their children's microbiomes.

Pesticide contamination in agro-ecosystems: toxicity, impacts, and bio-based management strategies

Continuous rise in application of pesticides in the agro-ecosystems in order to ensure food supply to the ever-growing population is of greater concern to the human health and the environment. Once entered into the agro-ecosystem, the fate and transport of pesticides is determined largely by the nature of pesticides and the soil attributes, in addition to the soil-inhabiting microbes, fauna, and flora. Changes in the soil microbiological actions, soil properties, and enzymatic activities resulting from pesticide applications are the important factors substantially affecting the soil productivity. Disturbances in the microbial community composition may lead to the considerable perturbations in cycling of major nutrients, metals, and subsequent uptake by plants. Indiscriminate applications are linked with the accumulation of pesticides in plant-based foods, feeds, and animal products. Furthermore, rapid increase in the application of pesticides having long half-life has also been reported to contaminate the nearby aquatic environments and accumulation in the plants, animals, and microbes surviving there. To circumvent the negative consequences of pesticide application, multitude of techniques falling in physical, chemical, and biological categories are presented by different investigators. In the present study, important findings pertaining to the pesticide contamination in cultivated agricultural soils; toxicity on soil microbes, plants, invertebrates, and vertebrates; effects on soil characteristics; and alleviation of toxicity by bio-based management approaches have been thoroughly reviewed. With the help of bibliometric analysis, thematic evolution and research trends on the bioremediation of pesticides in the agro-ecosystems have also been highlighted.

Pesticide exposure among Czech adults and children from the CELSPAC-SPECIMEn cohort: Urinary biomarker levels and associated health risks

Current-use pesticides (CUP) are extensively applied in both agricultural and urban settings. Exposure occurs mainly via the dietary pathway; however, other pathways such as inhalation or skin contact are also important. In this study, urinary levels of 12 CUP metabolites were investigated among 110 parent-child pairs during two seasons of 2020. Metabolites of pyrethroids (3-PBA, t/c-DCCA), chlorpyrifos (TCPY), and tebuconazole (TEB-OH) were detected in more than 60% of the samples. Chlorpyrifos metabolite was found at the highest concentration and tebuconazole was detected in almost all samples. CUP urinary metabolite levels were significantly higher in children in comparison to adults, except for tebuconazole, which was similar in both groups. In children, winter samples had significantly higher concentrations of pyrethroid and chlorpyrifos metabolites in comparison to the summer samples, but in adults, only chlorpyrifos metabolite concentrations were higher in the winter. No association between CUP urinary metabolite levels and proximity/surface of agricultural areas around residences was observed. Based on our findings, we suspect that CUP exposure is mainly driven by diet and that the effect of environmental exposure is less significant. Daily Intakes were estimated with three possible scenarios considering the amount of the metabolite excreted in urine and were compared to Acceptable Daily Intake values. Using a realistic scenario, exposure to chlorpyrifos exhibited the highest health risk, but still within a safe level. The Acceptable Daily Intake was exceeded only in one child in the case of cypermethrin. The cumulative risk assessment of pesticide mixtures having an effect on the nervous system, based on the total margin of exposure calculations, did not indicate any risk. The overall risk associated with pesticide exposure in the observed population was low. However, the risk observed using the worst-case scenario suggests the need for continuous evaluation of human exposure to such compounds, especially in children.

A Pilot Nationwide Survey on the Concentrations of Neonicotinoids and Their Metabolites in Indoor Dust from China: Application for Human Exposure

The present study assessed the residue levels of six parent neonicotinoids (p-NEOs) and four metabolites (m-NEOs) in indoor dust collected from 12 cities of China. Acetamiprid (ACE) and imidacloprid (IMI) were the predominated p-NEOs (detection rates: 98%) with the median values at 4.54 and 7.48 ng/g dry weight (dw), respectively. N-demethyl-acetamiprid (N-dm-ACE) was the most important m-NEO with the median value at 0.69 ng/g dw, while other m-NEOs were rarely detected (detection rates: < 15%). Significant correlation between ACE and thiacloprid (THD) was observed (p < 0.01), indicating their probably concurrent applications. ACE was significantly correlated to N-dm-ACE (p < 0.01), implicating the degradation of ACE in indoor environment. The estimated daily intake (EDI_ing) of NEOs via dust ingestion were far lower than the acceptable daily intake for NEOs. To our knowledge, this study provided a baseline nationwide investigation on the occurrence of NEOs in indoor dust of China.

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

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

Comparative study of neonicotinoid insecticides (NNIs) and NNI-Related substances (r-NNIs) in foodstuffs and indoor dust

Comparative studies of neonicotinoid insecticides (NNIs) and NNI-related substances (r-NNIs) in foodstuffs and indoor dust are rare. Herein, we investigated the feature fragmentations of nine NNIs in high-energy collision dissociation cells via high-resolution orbitrap mass spectrometry and observed that NNIs can consistently generate several feature fragments (e.g., C6H5NCl+, C4H3NSCl+, and C6H5NF3+). Consequently, NNIs and r-NNIs were comprehensively (targeted, suspect, and feature fragment-dependent) detected in 107 foodstuff and 49 indoor dust samples collected from Nanjing City (eastern China). We fully or tentatively identified 9 target NNIs and 5 r-NNIs in these samples. NNIs and r-NNIs were detected in 93.5% of the analyzed foodstuff samples, and high concentrations were detected in vegetables (mean: 409 ng/g wet weight [ww]) and fruits (127 ng/g ww). Regarding indoor dust, imidacloprid and acetamiprid exhibited extremely high detection frequencies and contamination levels, and the highest mean concentrations of NNIs and r-NNIs were detected in dormitory samples. Based on the NNI and r-NNI concentrations in the analyzed samples, the mean estimated daily intake values for Chinese adults and children via dietary intake and dust ingestion were 2080-8190 ng/kg bw/day and 378-2680 pg/kg bw/day, respectively.

Occurrence of azole and strobilurin fungicides in indoor dust from three cities of China

Widespread use of fungicides has raised the concern of exposure to them among the general population. However, there are extremely limited studies reporting the occurrence of fungicides in indoor dust in China. This study aimed to determine ten agricultural fungicides in indoor dust samples collected in three cities of China from 2016 to 2019, assess spatial and seasonal variations, and estimate the related exposure via dust ingestion. Six out of ten fungicides including difenoconazole, prochloraz, tebuconazole, tricyclazole, azoxystrobin, and pyraclostrobin were frequently detected in the dust samples (ranged 65.8-97.7%) and the concentrations of some fungicides showed a strong correlation with each other. Difenoconazole was the most abundant one among the selected fungicides. The highest level of the selected fungicides was observed in the indoor dust collected from Wuhan in summer 2019 (median cumulative concentration of the fungicides: 62.6 ng/g), while the relatively low concentrations of fungicides were found in the dust from Taiyuan (2.08 ng/g). Heavier fungicide contamination was observed in urban districts compared to that in rural districts. Seasonal variations in the fungicide residuals were also identified. The exposure assessment suggested that intake of the selected fungicides via dust ingestion was much lower than dietary intake reported in other studies. This study filled the data gap of fungicide residuals in the indoor dust in China and further studies are needed to identify the sources and determinants of indoor fungicide contamination.

Pesticides in doormat and floor dust from homes close to treated fields: Spatio-temporal variance and determinants of occurrence and concentrations

Indoor dust has been postulated as an important matrix for residential pesticide exposure. However, there is a lack of information on presence, concentrations and determinants of multiple pesticides in dust in residential homes close to treated fields. Our objective was to characterize the spatial and temporal variance of pesticides in house dust, study the use of doormats and floors as proxies for pesticides in indoor dust and identify determinants of occurrence and concentrations. Homes within 250 m from selected bulb fields were invited to participate. Homes within 20 km from these fields but not having agricultural fields within 500 m were selected as controls. House dust was vacuumed in all homes from floors (VFD) and from newly placed clean doormats (DDM). Sampling was done during two periods, when pesticides are used and not-used. For determination of 46 prioritized pesticides, a multi-residue extraction method was used. Most statistical analyses are focused on the 12 and 14 pesticides that were detected in >40% of DDM and VFD samples, respectively. Mixed models were used to evaluate relationships between possible determinants and pesticides occurrence and concentrations in DDM and VFD. 17 pesticides were detected in more than 50% of the homes in both matrixes. Concentrations differed by about a factor five between use and non-use periods among homes within 250 m of fields and between these homes and controls. For 7 pesticides there was a moderate to strong correlation (Spearman rho 0.30-0.75) between concentrations in DDM and VFD. Distance to agricultural fields and air concentrations were among the most relevant predictors for occurrence and levels of a given pesticide in DDM. Concentrations in dust are overall higher during application periods and closer to fields (<250 m) than further away. The omnipresence of pesticides in dust lead to residents being exposed all year round.

High Performance of Ionic-Liquid-Based Materials to Remove Insecticides

Neonicotinoids are systemic insecticides commonly used for pest control in agriculture and veterinary applications. Due to their widespread use, neonicotinoid insecticides (neonics) are found in different environmental compartments, including water, soils, and biota, in which their high toxicity towards non-target organisms is a matter of great concern. Given their widespread use and high toxicity, the development of strategies to remove neonics, while avoiding further environmental contamination is of high priority. In this work, ionic-liquid-based materials, comprising silica modified with tetraalkylammonium cations and the chloride anion, were explored as alternative adsorbent materials to remove four neonics insecticides, namely imidacloprid, acetamiprid, thiacloprid, and thiamethoxam, from aqueous media. These materials or supported ionic liquids (SILs) were first synthesized and chemically characterized and further applied in adsorption studies. It was found that the equilibrium concentration of the adsorbate in the solid phase decreases with the decrease in the SIL cation alkyl chain length, reinforcing the relevance of hydrophobic interactions between ionic liquids (ILs) and insecticides. The best-identified SIL for the adsorption of the studied insecticides corresponds to silica modified with propyltrioctylammonium chloride ([Si][N3888]Cl). The saturation of SILs was reached in 5 min or less, showing their fast adsorption rate towards all insecticides, in contrast with activated carbon (benchmark) that requires 40 to 60 min. The best fitting of the experimental kinetic data was achieved with the Pseudo Second-Order model, meaning that the adsorption process is controlled at the solid-liquid interface. On the other hand, the best fitting of the experimental isotherm data is given by the Freundlich isotherm model, revealing that multiple layers of insecticides onto the SIL surface may occur. The continuous removal efficiency of the best SIL ([Si][N3888]Cl) by solid-phase extraction was finally appraised, with the maximum adsorption capacity decreasing in the following sequence: imidacloprid > thiacloprid > thiamethoxam > acetamiprid. Based on real reported values, under ideal conditions, 1 g of [Si][N3888]Cl is able to treat at least 106 m3 of wastewater and water from wetland contaminated with the studied neonics. In summary, the enhanced adsorption capacity of SILs for a broad diversity of neonics was demonstrated, reinforcing the usefulness of these materials for their removal from aqueous matrices and thus contributing to preventing their introduction into the ecosystems and reducing their detrimental effects in the environment and human health.

Effects of imidacloprid on viability and increase of reactive oxygen and nitrogen species in HepG2 cell line

Imidacloprid (IMD) is a neonicotinoid insecticide used in large quantities worldwide in both veterinary and agronomic applications. Several studies have shown adverse effects of IMD on non-target organisms, with the liver being identified as the main affected organ. This study aimed to evaluate the effects of IMD on human hepatoblastoma (HepG2) cells. HepG2 were exposed to IMD (0.25-2.0 mM) for 24 and 48 h. IMD treatment resulted in cytotoxicity in the HepG2, inhibiting cell proliferation in a dose- and time-dependent manner, starting at concentrations of 0.5 mM (24 h) and 0.25 mM (48 h), and reducing cell viability from 0.5 mM onwards (24 and 48 h). IMD significantly decreased the mitochondrial membrane potential at both time points investigated (2.0 mM), and also induced damage to the cell membrane, demonstrated by significant dose and time-dependent increases in lactate dehydrogenase (LDH) release from concentrations of 1.0 mM (24 h) and 0.5 mM (48 h) upwards. IMD treatment also increased the production of reactive oxygen and nitrogen species (ROS/RNS) at rates above 50% following 0.5 mM (24 h) or 0.25 mM (48 h) concentrations, and caused a significant decrease in reduced/oxidized glutathione ratio (GSH/GSSG), indicating oxidative stress. Furthermore, the antioxidant dithiothreitol, which reacts with ROS/RNS and acts as a thiol reducing agent, inhibited the cytotoxic effect of IMD. In addition, the metabolite IMD-olefin was more toxic than IMD. Our results indicate that IMD induces cytotoxicity in HepG2 cells and that this effect may be associated with an increase in the generation of ROS/RNS.

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.

Relation between organophosphate pesticide metabolite concentrations with pesticide exposures, socio-economic factors and lifestyles: A cross-sectional study among school boys in the rural Western Cape, South Africa

Evidence on the relationship between lifestyle, socio-economic factors and pesticide exposure and urinary concentrations of organophosphate (OP) pesticide metabolites among children is generally incomplete. This study investigated the relationship between socio-economic factors and reported pesticide exposures and the sum of three urinary concentrations of dialkyl phosphate metabolites (DAP) among boys living in the rural areas of the Western Cape, South Africa. Data was collected during a cross-sectional study of 183 boys from three agricultural intense areas. Measurements included a questionnaire on socio-economic and pesticide exposures and urinary DAP concentrations. Most boys (70%) lived on farms with a median age of 12 years (range: 5.0-19.5 years). Children aged >14 years had lower DAP urine concentrations (median = 39.9 ng/ml; β = -68.1 ng/ml; 95% CI: -136.8, 0.6) than children aged 9 years and younger (median = 107.0 ng/ml). DAP concentrations also varied significantly with area, with concentrations in the grape farming area, Hex River Valley (median = 61.8 ng/ml; β = -52.1; 95% CI: -97.9, -6.3 ng/ml) and the wheat farming area, Piketberg (median = 72.4 ng/ml; β = -54.2; 95% CI: 98.8, -9.7 ng/ml) lower than those in the pome farming area, Grabouw (median = 79.9 ng/ml). Other weaker and non-significant associations with increased DAP levels were found with increased household income, member of household working with pesticides, living on a farm, drinking water from an open water source and eating crops from the vineyard and or garden. The study found younger age and living in and around apple and grape farms to be associated with increased urinary DAP concentrations. Additionally, there were other pesticide exposures and socio-economic and lifestyle factors that were weakly associated with elevated urinary DAP levels requiring further study. The study provided more evidence on factors associated to urinary DAP concentrations especially in developing country settings.

Profiles of urinary neonicotinoids and dialkylphosphates in populations in nine countries

The application of neonicotinoid insecticides (neonics) has increased dramatically as a replacement for organophosphate pesticides (OPs) in recent years. Nevertheless, little is known about human exposure to these pesticides in various countries. In this study, concentrations of 14 neonics and six dialkylphosphate metabolites (DAPs) were determined simultaneously in 566 urine samples collected from nine countries during 2010-2014. The highest sum concentration of 14 neonics was found in urine from Vietnam (median: 12.2 ng/mL) whereas that of six DAPs was from China (18.4 ng/mL). The median concentrations of ∑6 DAPs were twice higher than those of ∑14 neonics across the nine countries, which suggested a greater exposure to OPs than neonics. The overall pattern of urinary pesticide concentrations was similar among the nine countries with dimethylphosphate (DMP) and dimethylthiophosphate (DMTP) accounting for 51-89% of the total pesticide concentrations. Differences in urinary pesticide concentrations between genders (female and male), age groups (≤20, 21-49, and ≥50 years), and regions (cities of Shanghai, Guangzhou and Qiqihar) were examined. Total daily exposure doses to OPs were highest in China (515 μg/day) with 15% of the samples exceeding the U.S. Environmental Protection Agency's reference dose for chlorpyrifos (18 μg/day). This is the first study to establish baseline levels of OP and neonics exposure in general populations across nine countries.

Serum concentrations of pesticides including organophosphates, pyrethroids and neonicotinoids in a population with osteoarthritis in Saudi Arabia

Human exposure to pesticides is widespread and has received much attention in recent years because of its link to adverse health outcomes. Measurement of urinary concentrations of pesticides and their metabolites is often used in the assessment of body burdens of these chemicals. However, pesticides and their metabolites can be present in blood circulatory system, although little is known on serum levels of pesticides. In this study, we aimed to examine the occurrence and profile of four organophosphate (OP), five pyrethroid (PYR) insecticides, two phenoxy acid (PA) herbicides, 14 neonicotinoid (neonic) insecticides and six dialkylphosphate metabolites in serum from 25 individuals diagnosed with osteoarthritis in Jeddah, Saudi Arabia. 2-Isopropyl-4-methyl-6-hydroxypyrimidine (IMPY), 3,5,6-trichloro-2-pyridinol (TCPY), 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, 3-phenoxybenzoic acid, N-desmethyl acetamiprid, dimethylphosphate (DMP) and dimethylthiophosphate (DMTP) were detected in ≥80% of the serum samples analyzed. Metabolites of OPs, DMTP (median concentration: 2.14 ng/mL), DMP (1.04 ng/mL) and TCPY (0.84 ng/mL), collectively accounted for 67-83% of the total serum pesticide concentrations. Serum concentrations of pesticides were similar to or lower than those reported in urine. Our preliminary evidence suggests that serum can be used as a matrix for the assessment of exposure to OPs, PYRs, PAs and neonics.

Nanofibrillar cellulose/Au@Ag nanoparticle nanocomposite as a SERS substrate for detection of paraquat and thiram in lettuce

A nanocomposite based on nanofibrillar cellulose (NFC) coated with gold-silver (core-shell) nanoparticles (Au@Ag NPs) was developed as a novel surface-enhanced Raman spectroscopy (SERS) substrate. SERS performance of NFC/Au@Ag NP nanocomposite was tested by 4-mercaptobenzoic acid. The cellulose nanofibril network was a suitable platform that allowed Au@Ag NPs to be evenly distributed and stabilized over the substrate, providing more SERS hotspots for the measurement. Two pesticides, thiram and paraquat, were successfully detected either individually or as a mixture in lettuce by SERS coupled with the nanocomposite. Strong Raman scattering signals for both thiram and paraquat were obtained within a Raman shift range of 400-2000 cm-1 and a Raman intensity ~ 8 times higher than those acquired by NFC/Au NP nanocomposite. Characteristic peaks were clearly observable in all SERS spectra even at a low concentration of 10 μg/L of pesticides. Limit of detection values of 71 and 46 μg/L were obtained for thiram and paraquat, respectively. Satisfactory SERS performance, reproducibility, and sensitivity of NFC/Au@Ag NP nanocomposite validate its applicability for real-world analysis to monitor pesticides and other contaminants in complex food matrices within a short acquisition time. Graphical abstract.

Characterizing the Neurodevelopmental Pesticide Exposome in a Children's Agricultural Cohort

The exposome provides a conceptual model for identifying and characterizing lifetime environmental exposures and resultant health effects. In this study, we applied key exposome concepts to look specifically at the neurodevelopmental pesticide exposome, which focuses on exposures to pesticides that have the potential to cause an adverse neurodevelopmental impact. Using household dust samples from a children's agricultural cohort located in the Yakima Valley of Washington state, we identified 87 individual pesticides using liquid chromatography-tandem mass spectrometry. A total of 47 of these have evidence of neurotoxicity included in the Environmental Protection Agency (EPA) (re)registration materials. We used a mixed effects model to model trends in pesticide exposure. Over the two study years (2005 and 2011), we demonstrate a significant decrease in the neurodevelopmental pesticide exposome across the cohort, but particularly among farmworker households. Additional analysis with a non-parametric binomial analysis that weighted the levels of potentially neurotoxic pesticides detected in household dust by their reference doses revealed that the decrease in potentially neurotoxic pesticides was largely a result of decreases in some of the most potent neurotoxicants. Overall, this study provides evidence that the neurodevelopmental pesticide exposome framework is a useful tool in assessing the effectiveness of specific interventions in reducing exposure as well as setting priorities for future targeted actions.

Variability in urinary neonicotinoid concentrations in single-spot and first-morning void and its association with oxidative stress markers

Human exposure to neonicotinoid insecticides (hereafter "neonics") is a concern. Spot urine samples have been widely used in the assessment of exposure to neonics. Urinary concentrations, however, can vary greatly over time due to variable exposure, potentially leading to exposure misclassification. In this study, within- and between-individual variability of urinary concentrations of 13 neonics and their metabolites collected consecutively for up to 44 days from 19 individuals were examined. We also measured seven oxidative stress biomarkers (OSBs) in repeated urine samples to elucidate their relationship with neonic exposure by mixed regression models. Intraclass correlation coefficients (ICCs, a ratio of between-individual variance to total variance) were used to assess the reproducibility of neonic/metabolite concentrations. Sensitivity and specificity were used to evaluate how well spot urine samples determined an individual's average exposure over 44 days. A fair to good reproducibility was observed for N-desmethyl-acetamiprid (ICC = 0.42), whereas thiamethoxam, imidacloprid, clothianidin, imidaclothiz, 6-chloronicotinic acid, and sulfoxaflor showed poor reproducibility (ICC = 0.02-0.37). Use of single-spot urine samples to classify high (top 33%) exposure showed higher specificities (0.68-0.92) than sensitivities (0.32-0.88). The minimum number of specimens (k) required to estimate participant-specific mean for neonic exposures within 20% of the "true" values ranged from 16 to 172. Significant positive correlations were found between some of neonic and OSB concentrations. The high variability found in the urinary concentrations of most neonics/metabolites suggests that a single measurement can result in exposure misclassification.

Neonicotinoids and carbendazim in indoor dust from three cities in China: Spatial and temporal variations

Neonicotinoid insecticides (NNIs) are a relatively new class of insecticides, and carbendazim (CBDZ) is a representative antifungal biocide. The occurrence of them in indoor dust was not documented in China. In this study, 336 indoor dust samples were collected from 3 cities, including Taiyuan (October 2016), Wuhan (October 2016 and 2018), and Shenzhen (February 2019), located in North, Central, and South China, for determination of the residues of six NNIs, two of their metabolites, and CBDZ. Acetamiprid (ACE), imidacloprid (IMI), and CBDZ were found to be the major target analytes in dust samples from all selected cities with detection frequencies of 98.8%, 99.7%, and 95.2%, respectively. At least one target NNI was detected for all of the dust samples, with the median concentration of 25.8 ng/g for the imidacloprid-equivalent total neonicotinoids (IMI_eq: generated by the relative potency factor method), and the median for CBDZ was 35.8 ng/g. Higher levels of several NNIs and CBDZ were found in urban areas of Taiyuan and Wuhan than those in rural areas. A significant increase of the NNI residues was observed in dust of Wuhan from 2016 to 2018 (while not significant for CBDZ). Finally, the estimated daily intake (EDI) of IMI_eq and CBDZ for infants and toddlers were higher than that found in other age groups through dust ingestion, which indicated that infants and toddlers may be susceptible to current residue of NNIs and CBDZ in indoor dust, and dust ingestion of NNIs might be <1% of that reported for dietary intakes in China. This is the first study to report the residue levels of NNIs and CBDZ in dust samples from indoor environment in China.