Exposure of Male Farmers and Nonfarmers to Neonicotinoid Pesticides in the South-West and Littoral Regions of Cameroon: A Comparative Study.

Pesticides, especially the newly developed neonicotinoids, are increasingly used in many countries around the world, including Cameroon, to control pests involved in crop destruction or disease transmission. Unfortunately, the pesticides also pose tremendous environmental problems because a predominant amount of their residues enter environmental matrices to affect other nontargeted species including humans. This therefore calls for continuous biomonitoring of these insecticides in human populations. The present study sought to assess the neonicotinoid insecticide exposures in two agrarian regions of Cameroon, the South-West region and Littoral region. The study involved 188 men, including 125 farmers and 63 nonfarmers. Spot urine samples were obtained from these subjects and subjected to liquid chromatographic-tandem mass spectrometric analysis for concentrations of neonicotinoid compounds, including acetamiprid, clothianidin, dinotefuran, imidacloprid, thiacloprid, nitenpyram, thiamethoxam, and N-dm-acetamiprid. Neonicotinoid compounds were detected in all study participants, and residues of all the screened pesticides were detected among participants. N-dm-Acetamiprid and imidacloprid were the most prevalent among the subjects (100.0% and 93.1%, respectively), whereas nitenpyram was less common (3.2%). The median values of imidacloprid and total urinary neonicotinoid concentrations were elevated among farmers (0.258 vs. 0.126 µg/L and 0.829 vs. 0.312 µg/L, respectively). Altogether the findings showed that both the farmer and nonfarmer study populations of Cameroon were exposed to multiple residues of neonicotinoids, with relatively higher levels of pesticides generally recorded among farmers. Although exposure levels of the neonicotinoids were generally lower than their respective reference doses, these results warrant further research on the health risk evaluation of multiple residues of the pesticides and reinforcement of control measures to minimize the exposure risks, especially among farmers. Environ Toxicol Chem 2024;43:952-964. © 2024 SETAC.

Urinary neonicotinoids and metabolites are associated with obesity risk in Chinese school children.

BACKGROUND: Neonicotinoids are the most widely used insecticides. Laboratory studies have suggested that neonicotinoids are one potential obesogen, but relevant data are limited in human. OBJECTIVE: To examine the association between exposure to neonicotinoids and childhood obesity. METHODS: We investigated 442 children in Shanghai, East China and measured eight neonicotinoids (thiamethoxam, clothianidin, acetamiprid, imidacloprid, thiacloprid, nitenpyram, dinotefuran, and imidaclothiz) and four metabolites (N-desmethyl-thiamethoxam, N-desmethyl-clothianidin, N-desmethyl-acetamiprid, and 5-OH-imidacloprid) in urine. Body mass index (BMI) and waist circumference (WC) were used to identify general overweight/obesity and central obesity, respectively. Linear and logistic regression models based on generalized estimating equations were used to investigate the associations of urinary neonicotinoids and metabolites with BMI z-score, WC z-score, general overweight/obesity, and central obesity. RESULTS: Children with a positive detection of clothianidin and its metabolite had a marginally higher BMI z-score (regression coefficient (ß): 0.08, 95% confidence interval (95% CI): 0.01, 0.14) after adjusted for relevant covariates. After creatinine-adjusted concentration was trichotomized, compared to children with a negative detection, children in the high urinary concentration of acetamiprid and its metabolite had a low BMI z-score (ß: -0.19, 95%CI: -0.30, -0.08), children in the medium urinary concentration of neonicotinoids and metabolites other than thiamethoxam, clothianidin, acetamiprid, and their metabolites had a marginally higher BMI z-score (ß: 0.25, 95%CI: 0.03, 0.46), a higher WC z-score (ß: 0.24, 95%CI: 0.14, 0.33), and a higher odds of central obesity (odds ratio (OR): 2.16, 95% CI: 1.28, 3.63), and children in the medium urinary concentration of all neonicotinoids and metabolites had a higher odds of central obesity (OR: 1.55, 95%CI: 1.04, 2.33). Some associations showed sex- and age- related differences. CONCLUSION: Urinary neonicotinoids and metabolites were found to be differently associated with obesity-related indexes, which suggested that exposure to neonicotinoids might have a mixed effect on childhood obesity.

Within-person variability of urinary neonicotinoids and their metabolites and recommendation for sampling strategy.

Humans are exposed to neonicotinoid insecticides (NEOs) from various routes. Urine has been widely used to characterize the internal exposure levels of NEOs in humans. However, variable sampling methods can result in highly variable measurements of NEOs, potentially leading to misunderstanding of human exposure. In this study, we collected the first morning voids urine (FMVU), spot urine (SU), and 24 h urine (24hU) samples from 8 healthy adults during 7 consecutive days. The concentration, variability, and reproducibility of six parent NEOs (p-NEOs) and three NEOs metabolites (m-NEOs) were measured. Over 79 % of the urine samples had detectable levels of NEOs. Dinotefuran (DIN) and olefin-imidacloprid (of-IMI) were excreted in the highest concentration of p-NEO and m-NEO, respectively. All of the p-NEOs except thiacloprid (THD) and of-IMI were recommended as biomarkers for biomonitoring studies. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were used to evaluate the temporal variability and reproducibility of urinary NEOs in SU, FMVU and 24hU, respectively. We observed low ICCs ranging from 0.016 to 0.39 for NEOs regardless of the sample types. However, the higher CV and lower ICC values observed in SU samples suggested lower reproducibility compared to FMVU and 24hU samples. Significant correlations of several NEOs between FMVU and 24hU were also observed in the current study. Considering the comparable concentrations and similarity between FMVU and 24hU, our study proposed possible biomarkers and indicated that the potential for FMVU samples to estimate adequately an individual's exposure to NEOs. Therefore, we suggested FMVU as a sampling strategy in future human biomonitoring studies, while multiple samples were recommended to detect exposure over time intervals of weeks or months.

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.

Urinary concentrations of neonicotinoid insecticides were related to renal tubular dysfunction and neuropsychological complaints in Dry-zone of Sri Lanka.

Neonicotinoids are systemic insecticides used since the 1990's , that possess renal tubular toxicity. We conducted a field-based descriptive study in the North Central Dry-zone of Sri Lanka, where chronic kidney disease (CKD) of unknown etiology has been increasing since the 1990's. To elucidate the relationship between renal tubular dysfunctions and urinary neonicotinoids concentrations, we collected spot urine samples from15 CKD patients, 15 family members, and 62 neighbors in 2015, analyzed two renal tubular biomarkers, Cystatin-C and L-FABP, quantified seven neonicotinoids and a metabolite N-desmethyl-acetamiprid by LC-MS/MS; and we investigated their symptoms using a questionnaire. Cystatin-C and L-FABP had a positive correlation (p < 0.001). N-Desmethyl-acetamiprid was detected in 92.4% of the urine samples, followed by dinotefuran (17.4%), thiamethoxam (17.4%), clothianidin (9.8%), thiacloprid and imidacloprid. Dinotefuran and thiacloprid have never been registered in Sri Lanka. In High Cystatin-C group (> 70 µg/gCre, n = 7), higher urinary concentration of dinotefuran (p = 0.009), and in Zero Cystatin-C group (< LOQ, n = 7), higher N-desmethyl-acetamiprid (p = 0.013), dinotefuran (p = 0.049), and thiacloprid (p = 0.035), and more complaints of chest pains, stomachache, skin eruption and diarrhea (p < 0.05) were found than in Normal Cystatin-C group (n = 78). Urinary neonicotinoids may be one of the potential risk factors for renal tubular dysfunction in this area.

Biomonitoring method for neonicotinoid insecticides in urine of non-toilet-trained children using LC-MS/MS.

There is a growing appreciation of the importance of determining chemical exposure levels in early childhood, as well as in embryonic and foetal life, which are now widely believed to be essential for gaining insight into potential health risks associated with these chemicals. To facilitate the assessment of exposure to neonicotinoid insecticides (NEOs) in non-toilet-trained children, a new method using disposable diapers (nappies) was developed for the simultaneous determination of the NEOs acetamiprid and its metabolite N-desmethylacetamiprid, clothianidin, dinotefuran, imidacloprid, thiacloprid, and thiamethoxam (NEO biomarkers). The urine absorbed in disposable diapers was extracted with acetone (diaper urine) and was cleaned using a solid-phase extraction column, before analysis with LC-MS/MS. The absolute recoveries of NEO biomarkers were 19-50%. Good results were observed for the linearity of the matrix-matched calibration curves (r2 = 0.983-0.996; concentration range LOQ-20 µg L-1) and the precision of intra-day (% relative standard deviation (%RSD): 3.3-12.7%) and inter-day (%RSD: 4.3-19.5%) analyses. The lowest and highest limits of detection of the developed method were 0.07 µg L-1 for acetamiprid and 0.75 µg L-1 for clothianidin. The developed method was applied for the evaluation of fifty diapered three-year-old children in Japan. Importantly, the study revealed relatively high detection rates for dinotefuran and N-desmethylacetamiprid; 84% and 78% respectively. The highest geometric mean of dinotefuran urinary concentration was 2.01 µg L-1. Thus, a method for determining NEO biomarkers in urine extracted from disposable diapers was established. This is the first report on the simultaneous quantitative analysis of NEO biomarkers of diaper-absorbed urine samples.

A nationwide survey of urinary concentrations of neonicotinoid insecticides in China.

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

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

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

LC-ESI/MS/MS analysis of neonicotinoids in urine of very low birth weight infants at birth.

OBJECTIVES: Neonicotinoid insecticides are widely used systemic pesticides with nicotinic acetylcholine receptor agonist activity that are a concern as environmental pollutants. Neonicotinoids in humans and the environment have been widely reported, but few studies have examined their presence in fetuses and newborns. The objective of this study is to determine exposure to neonicotinoids and metabolites in very low birth weight (VLBW) infants. METHODS: An analytical method for seven neonicotinoids and one neonicotinoid metabolite, N-desmethylacetamiprid (DMAP), in human urine using LC-ESI/MS/MS was developed. This method was used for analysis of 57 urine samples collected within 48 hours after birth from VLBW infants of gestational age 23-34 weeks (male/female = 36/21, small for gestational age (SGA)/appropriate gestational age (AGA) = 6/51) who were admitted to the neonatal intensive care unit of Dokkyo Hospital from January 2009 to December 2010. Sixty-five samples collected on postnatal day 14 (M/F = 37/22, SGA/AGA = 7/52) were also analyzed. RESULTS: DMAP, a metabolite of acetamiprid, was detected in 14 urine samples collected at birth (24.6%, median level 0.048 ppb) and in 7 samples collected on postnatal day 14 (11.9%, median level 0.09 ppb). The urinary DMAP detection rate and level were higher in SGA than in AGA infants (both p<0.05). There were no correlations between the DMAP level and infant physique indexes (length, height, and head circumference SD scores). CONCLUSION: These results provide the first evidence worldwide of neonicotinoid exposure in newborn babies in the early phase after birth. The findings suggest a need to examine potential neurodevelopmental toxicity of neonicotinoids and metabolites in human fetuses.

Cohort-friendly protocol for the determination of two urinary biomarkers of exposure to pyrethroids and neonicotinoids using gas chromatography-triple quadrupole mass spectrometry.

Neonicotinoids (NEOs) and synthetic pyrethroids (PYRs) are active ingredients of commercial pesticides and/or insecticides with extensive indoor and outdoor applications, worldwide. Improved exposure metrics are warranted for NEOs and PYRs, if we are to better understand their human health effects. A cohort-friendly protocol for determining non-specific biomarkers of exposure to NEOs and PYRs, e.g. 6-chloronicotinic acid (6-CN) and 3-phenoxybenzoic acid (3-PBA), respectively, in human urine voids was proposed. A series of optimization experiments were conducted to validate the bioanalytical protocol using gas chromatography coupled with triple quadrupole mass spectrometry (GC-QqQ-MS/MS) in MRM mode. The method reached low detection limits for both analytes (0.075 µg L-1 for 6-CN and 0.050 µg L-1 for 3-PBA) in a short preparation and analysis time. The method used small initial urine sample volume (2 mL), short extraction time (≈ 240 min for the batches of 32 samples) and instrumental analysis time (≈ 14 min) for both pesticide metabolites in a single run. This protocol could facilitate the assessment of population exposure metrics for these pesticides and their inclusion in health risk assessment. Graphical abstract.

Urinary monitoring of neonicotinoid imidacloprid exposure to pesticide applicators.

Neonicotinoid pesticides have recently drawn attention worldwide owing to their potential adverse effects on non-target organisms and ecosystems. Exposure to imidacloprid, the most widely used neonicotinoid insecticide, is of particular concern among rural populations because of its ubiquitous use in agriculture. Hence, biological monitoring of urinary imidacloprid and its major metabolite 6-chloronicotinic acid (6-CNA) was performed using Polar Enhanced Polymer solid-phase extraction by LC-MS/MS with mean recoveries of 78.3-109.8% and limits of quantitation at 0.029-0.038 ng/mL. Imidacloprid was detected in 100% of urine samples from rural applicators at concentrations of 0.21-8.91 ng/mL (0.06-9.60 µg/g creatinine) and 0.11-24.58 ng/mL (0.66-57.40 µg/g creatinine) before and after pesticide application, respectively. Significant increase in urine concentration (3.52- to 3.77-fold) of imidacloprid and 6-CNA was observed after local imidacloprid field application (p ≤ 0.001). The estimated absorbed daily dose (ADD) for imidacloprid was 0.52-248.05 µg/kg/d, indicating that attention should be paid to potential health risks for applicators because of increased imidacloprid exposure at level of significance (p < 0.05). This study is the first to report ADD estimation for imidacloprid, thereby providing an important reference for further human health risk evaluation.

Quantification of DEET and neonicotinoid pesticide biomarkers in human urine by online solid-phase extraction high-performance liquid chromatography-tandem mass spectrometry.

Neonicotinoid insecticides are widely used replacements for organophosphate and carbamate insecticides, but the extent of human exposure is largely unknown. On the other hand, based on urinary concentrations of DEET metabolites, human exposure to N,N-diethyl-m-toluamide (DEET) appears to be widespread. We developed a fast online solid-phase extraction high-performance liquid chromatography-isotope dilution tandem mass spectrometry (HPLC-MS/MS) method to measure in 200 µL of human urine the concentrations of six neonicotinoid biomarkers (acetamiprid, N-desmethyl-acetamiprid, clothianidin, imidacloprid, 5-hydroxy-imidacloprid, thiacloprid), and two DEET biomarkers (3-diethyl-carbamoyl benzoic acid, 3-ethyl-carbamoyl benzoic acid). Limits of detection ranged from 0.01 to 0.1 µg/L, depending on the biomarker. Accuracy ranged from 91 to 116% and precision ranged from 3.7 to 10 %RSD. The presented method can be used to increase our understanding of exposure to neonicotinoid insecticides and DEET, and to evaluate the potential health effects from such exposures.

Exposures of children to neonicotinoids in pine wilt disease control areas.

Neonicotinoid insecticides that have been on the market since 1992 have been used globally including in Japan. Because they are sprayed over forests and agricultural areas, inadvertent toxicity in nontarget insects (especially honey bees) and humans is a matter of public concern. However, information on exposure levels and potential health impacts of neonicotinoids in children living around sprayed areas is scarce. Thus, we determined neonicotinoid exposure levels in children living in communities where thiacloprid was used to control pine wilt disease. A total of 46 children (23 males and 23 females) were recruited for the present study, and informed written consent was obtained from their guardians. Urine specimens were collected before, during, and after insecticide spraying events; and atmospheric particulate matter was also collected. Concentrations of thiacloprid and 6 other neonicotinoid compounds were determined in urine samples and in atmospheric particulate matter specimens using liquid chromatography-electrospray ionization-tandem mass spectrometry. In urine specimens, thiacloprid concentrations were <0.13 µg/L and were detectable in approximately 30% of all samples. Concentrations of the other neonicotinoids, N-dm-acetamiprid, thiamethoxam, dinotefuran, and clothianidin, were 18.7, 1.92, 72.3, and 6.02 µg/L, respectively. Estimated daily intakes of these neonicotinoids were then calculated from urinary levels; although the estimated daily intakes of the neonicotinoids were lower than current acceptable daily intake values, the children were found to be exposed to multiple neonicotinoids on a daily basis. Environ Toxicol Chem 2019;38:71-79. © 2018 SETAC.

Simultaneous determination of nine neonicotinoids in human urine using isotope-dilution ultra-performance liquid chromatography-tandem mass spectrometry.

Neonicotinoids (neonics), a class of systemic insecticides, have been frequently detected in pollen, vegetables, and fruits. Recently, an increasing concern has been aroused for human exposure to neonics. However, biological monitoring for quantifying body burden of neonics has rarely been reported. In this study, we developed an isotope-dilution ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method to simultaneously quantify nine neonics, including acetamiprid (ACE), thiamethoxam (THIAM), imidacloprid (IMIP), clothianidin (CLO), flonicamid (FLO), thiacloprid (THIAC), dinotefuran (DIN), nitenpyram (NIT), and imidaclothiz (IMIT) in urine. The limits of quantification were 0.1 µg/L for ACE, FLO, DIN, NIT and IMIT, and 0.2 µg/L for THIAM, IMIP, CLO, and THIAC. The overall recoveries were 80.8-103%, 81.5-91.7% and 83.0-92.3% for QA/QC samples fortifying at 1, 25, and 100 µg/L levels, respectively. UPLC/MS/MS method was used to analyze urine samples obtained from 10 children in Hangzhou, China. The detection frequencies were 80% for ACE and IMIP, 70% for THIAM and CLO, 20% for DIN and IMIT and 10% for THIAC. FLO and NIT were not detected in those urine samples. The data provided here will be helpful for conducting biological monitoring of neonics exposure in the future.

Semiautomated determination of neonicotinoids and characteristic metabolite in urine samples using TurboFlow™ coupled to ultra high performance liquid chromatography coupled to Orbitrap analyzer.

A semiautomated method based on ultra-high performance liquid chromatography (UHPLC) coupled to Orbitrap high resolution mass spectrometry has been developed for the determination of neonicotinoids (imidacloprid, acetamiprid, clothianidin, dinotefuran, nitenpyram, thiacloprid and thiamethoxam) and the metabolite acetamiprid-n-desmethyl in urine samples. Two automated methods were tested (solid-phase extraction "SPE" and turbulent flow chromatography "TurboFlow™"), obtaining the best results when TurboFlow™ was applied. The total analysis time for the developed method was 14min. The optimized method was validated, obtaining suitable results for all validation parameters. Recoveries ranged from 78% to 116% meanwhile repeatability and reproducibility were evaluated obtaining values lower than 10% and 20% respectively (except for dinotefuran and nitenpyram at 0.2µgL-1). The limit of quantification (LOQ) for all compounds was established at 0.2µgL-1. The proposed analytical methodology was applied to analyze the target compounds in thirty six urine samples from pregnant women living in agricultural areas of Almería (Spain). Imidacloprid, acetamiprid and acetamiprid-n-desmethyl were detected in some of the samples at concentrations ranging from 0.23 to 1.57µgL-1. Furthermore, dinotefuran was identified in two samples at trace levels.

Insecticides of neonicotinoides class: determining exposure via workers' urine.

For biomonitoring of exposure in workers with insectocaricides, the authors created a method of multi-component assessment oflowlevels of neonicotinomides in workers' urine, based on last generation tandem liquid mass-spectrometry (triple quadrupole) with ionization source - electrostatic dispersion (positive ionization) in dynamic multi-reaction monitoring with two transitions of parent ions (for quantitative assessment and ionic ratio confirmation). After the work, the operators gave urine samples (about 100 ml in average) that were frozen and kept under -20°C before analysis. Samples were defrozen before analysis, and each urine portion of 5 ml was diluted by equal volume of 0,1% formic acid. To extract substances out of the samples, solid-phase extraction (cartridges based on octadecylsilane) was applied, elution was performed with 1 ml of methanol. Lower limit of the substances detection in urine - 0,02-0,05 ng/ml, lower limit of the quantitative assessment - 0,1-0,2 ng/ml. The method was tested on monitoring of the workers' exposure to preparations based on imidaclopride and clotianidine in natural conditions of pesticides use in agriculture with various processing technologies. midacloprid was identified in urine of 3 professional operators after wheat and oat seeds treatment and after subsequent seeding at lower limit of detection (0,02 ng/ml), lower limit of quantitative assessment (0,1 ng/ ml) and 0,34 ng/ml.

Biomonitoring and exposure levels of imidacloprid in air of workplace and on skin of workers exposed to pesticides.

The article presents results ofhygienic studies on work conditions in using imidacloprid-based pesticides in agriculture. Analysis covered imidacloprid levels in air of workplace, on skin and in urine of workers.