Rapid quantification of seven major neonicotinoids and neonicotinoid-like compounds and their key metabolites in human urine

Determination of twelve neonicotinoid pesticides in chili using an improved QuEChERS method with UPLC-Q-TOF/MS

In this study, a QuEChERS method based on citrate was developed and utilized for the analysis of twelve neonicotinoid pesticides in fresh red chilies, fresh green chilies, and dried chilies, coupled with ultra-high performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-Q-TOF/MS). In the sample preparation, acetonitrile containing 1% formic acid was used as the extraction solvent. Anhydrous sodium sulfate replaced the traditional anhydrous magnesium sulfate for water removal, effectively eliminating the issues of salt caking. Graphitized carbon black, octadecyl silica, and primary secondary amine were used as cleaning agents. The method showed good sensitivity, with the limits of quantification below 0.03 mg/kg for fresh chilies and below 0.15 mg/kg for dried chilies. Values of matrix effects ranged from -19.5% to 8.4%, and the recovery was 86.9% - 105.2%. The analytical method provided an effective tool for the high throughput detection of neonicotinoid pesticide residues in multiple chili matrices.

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, distribution, and health risk assessment of pyrethroid and neonicotinoid insecticides in aquatic products of China

Synthetic pyrethroid insecticides (SPIs) and neonicotinoid insecticides (NEOs), now dominant in the insecticide market, are increasingly found in aquatic environments. This study focused on six SPIs and five NEOs in aquatic products from four Chinese provinces (Shandong, Hubei, Shanxi and Zhejiang) and the risk assessment of the safety for the residents was conducted. It revealed significantly higher residues of Σ6SPIs (6.27-117.19 μg/kg) compared to Σ5NEOs (0.30-14.05 μg/kg), with SPIs more prevalent in fish and NEOs in shellfish. Carnivorous fish showed higher pesticide levels. Residues of these two types of pesticides were higher in carnivorous fish than in fish with other feeding habits. In the four regions investigated, the hazard quotient and hazard index of SPIs and NEOs were all <1, indicating no immediate health risk to human from single and compound contamination of the two types of pesticides in aquatic products. The present study provides valuable information for aquaculture management, pollution control and safeguarding human health.

A novel method for the accurate quantification of two isomeric mercapturic acids of 1,3-dichlorobenzene in human urine using isotope dilution online-SPE-LC-MS/MS

1,3-dichlorobenzene (1,3-DCB) is an aromatic solvent that might be formed during thermal decomposition of bis(2,4-dichlorobenzoyl)peroxide used as initiator in silicone rubber production with many workers exposed worldwide. During metabolism of 1,3-DCB, two isomeric mercapturic acids can be formed from ring oxidation of 1,3-DCB in the liver, namely 2,4-dichlorophenylmercapturic acid (24CPhMA) and 3,5-dichlorophenylmercapturic acid (35CPhMA). These urinary mercapturic acids might serve as biomarkers of the toxicologically relevant absorbed dose of 1,3-DCB and have not been determined so far. Thus, we were aimed to develop an analytical method for quantification of these biomarkers. Authentic standards of both mercapturic acids as well as deuterium-labelled analogues were self-synthesized. A method for the quantification of both CPhMAs in human urine using online-SPE LC/MS/MS was developed and validated with an LOQ of 0.1 ng mL-1 for both CPhMAs. The analytes were extracted from urine by online-SPE on a restricted access material phase, transferred to the analytical column and quantified by tandem mass spectrometry. Interday (n = 6) and Intraday (n = 10) precision for both CPhMAs ranged from 1.7 to 4.3 % with accuracies between 99.4 and 109.9 % at concentrations of 0.6 and 3 ng mL-1. We applied the method on post-shift urine samples of 16 workers of the silicone rubber industry with occupational exposure to 1,3-DCB. Both CPhMAs were above LOQ in 15 of 16 urine samples with median levels (range) for 24CPhMA and 35CPhMA of 1.64 ng mL-1 (<0.1 - 8.2 ng mL-1) and 3.98 ng mL-1 (0.36 - 24.1 ng mL-1), respectively. This is the first report on specific urinary mercapturic acids of 1,3-DCB in humans. Our results show that ring oxidation of 1,3-DCB is considered to be a toxicologically relevant metabolic pathway in humans. This might improve risk assessment of 1,3-DCB-emissions in silicone rubber industry.

Human biomonitoring of neonicotinoid exposures: case studies after the use of a spray-agent to ornamental plants and a topical medication to pets

Acetamiprid (ACE) and imidacloprid (IMI) are insecticides of global importance and are used as spray and watering agents for ornamental plants to control biting and sucking insects or as topical medications on pets to remove and control fleas. Human biomonitoring data on ACE and IMI exposures when applying these products are limited. We investigated exposures to ACE and IMI in male volunteers after the domestic application of either an ACE-containing agent or an IMI-containing spot-on medication. Complete and consecutive urine samples were collected for up to 56 h after application. Urine samples were analyzed for ACE, IMI, and their respective metabolites (N-desmethyl-ACE, IMI-olefin, and sum of 4-/5-hydroxy-IMI) by liquid chromatography-tandem mass spectrometry. Fairly uniform concentrations of N-desmethyl-ACE could be observed before and after orchid treatment, so that an ACE exposure associated with orchid treatment can most likely be excluded. In contrast, after the application of the IMI-containing medication, elevated concentrations of IMI, 4-/5-hydroxy-IMI, and IMI-olefin were quantified in urine samples post-20 h with maximum concentrations of 3.1, 14.9, and 8.0 μg/g creatinine, respectively, well above general background levels. Nevertheless, the IMI intake (10.6 μg/kg bw), calculated from the excreted amounts, was around five times below the current European acceptable daily intake. Based on the case results here, household exposures to ACE and IMI after spray treatment of ornamental plants and anti-flea treatment of dogs can be regarded as low and safe. However, people regularly applying neonicotinoid-containing formulations, such as professional gardeners and employees in animal shelters, should be studied in more detail.

Quantitative Metabolism and Urinary Elimination Kinetics of Seven Neonicotinoids and Neonicotinoid-Like Compounds in Humans

Reverse dosimetry, i.e., calculating the dose of hazardous substances that has been taken up by humans based on measured analyte concentrations in spot urine samples, is critical for risk assessment and requires metabolic and kinetic data. We quantitatively studied the metabolism of seven major neonicotinoid and neonicotinoid-like compounds (NNIs) after single oral doses in male volunteers and determined key kinetic parameters and urinary elimination for NNIs together with their metabolites. Complete and consecutive urine samples were collected over 48 h. All samples were analyzed by tandem mass spectrometry, following liquid or gas chromatographic separation. Single- and group-specific NNI metabolites were quantified, i.e., hydroxylated and N-dealkylated NNIs and NNI-associated carboxylic acids and their glycine derivatives. Large, substance-dependent variations of key toxicokinetic parameters were observed. Mean times of concentration maxima (tmax) in urine varied between 2.0 (imidacloprid) and 25.8 h (N-desmethyl-clothianidin), whereas mean urinary elimination half-times (t1/2) were between 2.5 (acetamiprid) and 49.5 h (sulfoxaflor). Mean 48 h excretion fractions (Fue's) were between 0.03% (2-chloro-1,3-thiazole-5-carboxylic acid glycine) and 84% (clothianidin). In contrast, the interindividual differences of Fue's between the volunteers for each of the NNIs and their metabolites remained low (below a factor of 2 between the maximum and minimum derived Fue with the exception of 6-chloronicotinic acid in the acetamiprid dose study). The obtained quantitative data enabled choosing appropriate biomarkers for exposure assessment and, at the same time, for risk assessment by reverse dosimetry at current environmental exposures, i.e., comparing the calculated doses that have been taken up to currently available acceptable daily intakes of NNIs.

Comprehensive profiling and semi-quantification of exogenous chemicals in human urine using HRMS-based strategies

Chemicals infiltrate our daily experiences through multiple exposure pathways. Human biomonitoring (HBM) is routinely used to comprehensively understand these chemical interactions. Historically, HBM depended on targeted screening methods limited to a relatively small set of chemicals with triple quadrupole instruments typically. However, recent advances in high-resolution mass spectrometry (HRMS) have facilitated the use of broad-scope target, suspect, and non-target strategies, enhancing chemical exposome characterization within acceptable detection limits. Despite these advancements, establishing robust and efficient sample treatment protocols is still essential for trustworthy broad-range chemical analysis. This study sought to validate a methodology leveraging HRMS-based strategies for accurate profiling of exogenous chemicals and related metabolites in urine samples. We evaluated five extraction protocols, each encompassing various chemical classes, such as pharmaceuticals, plastic additives, personal care products, and pesticides, in terms of their extraction recoveries, linearity, matrix effect, sensitivity, and reproducibility. The most effective protocol was extensively validated and subsequently applied to 10 real human urine samples using wide-scope target analysis encompassing over 2000 chemicals. We successfully identified and semi-quantified a total of 36 chemicals using an ionization efficiency-based model, affirming the methodology's robust performance. Notably, our results dismissed the need for a deconjugation step, a typically labor-intensive and time-consuming process.

Quantitation of 6-chloronicotinic acid and 2-chloro-1,3-thiazole-5-carboxylic acid and their glycine conjugates in human urine to assess neonicotinoid exposure

Neonicotinoids and neonicotinoid-like compounds (NNIs) are widely used insecticides and their ubiquitous occurrence in the environment requires methods for exposure assessment in humans. The majority of the NNIs can be divided into 6-chloropyridinyl- and 2-chlorothiazolyl-containing compounds, suggesting the formation of the group-specific metabolites 6-chloronicotinic acid (6-CNA), 2-chloro-1,3-thiazole-5-carboxylic acid (2-CTA), and their respective glycine derivatives (6-CNA-gly, 2-CTA-gly). Here, we developed and validated an analytical method based on gas chromatography coupled to mass spectrometry (GC-MS/MS) to simultaneously analyze these four metabolites in human urine. As analytical standards for the glycine conjugates were not commercially available, we synthesized 6-CNA-gly, 2-CTA-gly, and their ¹³C₂,¹⁵N-labeled analogs for internal standardization and quantitation by stable isotope dilution. We also ensured chromatographic separation of 6-CNA and its isomer 2-CNA. Enzymatic cleavage during sample preparation was proven unnecessary. The limits of quantitation were between 0.1 (6-CNA) and 0.4 μg/L (2-CTA-gly) and the repeatability was satisfactory (coefficient of variation was <19% over the calibration range). We analyzed 38 spot urine samples from the general population and were able to quantify 6-CNA-gly in 58% of the samples (median 0.2 μg/L). In contrast, no 6-CNA could be detected. The results are in line with well-known metabolic pathways specific in humans, that, compared to rodents, favor the formation and excretion of phase-II-metabolites (glycine derivatives) rather than phase-I metabolites (free carboxylic acids). Nevertheless, the exact source of exposure (i.e., the specific NNI) remains elusive in the general population, may even vary quantitatively between different NNIs, and also might be regional specific based on the respective use of individual NNIs. In sum, we developed a robust and sensitive analytical method for the determination of four group-specific NNI metabolites.