| Neonicotinoid insecticides have become the varieties with the largest market share,and imidacloprid is the typical neonicotinoid with the largest usage in agricultural orchards.Pesticide applicators in agricultural orchards have relatively weak health and safety awareness during spraying,and often lack of appropriate protective measures,besides,rural residents may also have indirect exposure to imidacloprid via routes of dietary intake,air inhalation and dermal contact because of long living adjacent to agricultural areas.To conduct the health risk evaluation of imidacloprid exposure in rural populations,this study explored the exposure characteristics of imidacloprid in the urine of humans from agricultural orchards in China,and revealed the exposure difference and metabolism rule of imidacloprid in human urines before and after imidacloprid application.The main results are as follows:The 119 orchard planting families in typical agricultural orchard in Henan province were investigated,including 119 pesticide applicators and 156 family members.In addition,247 kindergarten children who had schooling adjacent to the orchard were also selected.Meanwhile,urban residents and urban kindergarten children was surveyed for comparative analysis.Total of 617 volunteers were participated and 1926 urine samples were collected.An analytical method for the determination of imidacloprid and its metabolite 6-chloronicotinic acid(6-CNA)in urine was established.The established method exhibited good linearity with R2 ? 0.9929,and the average recoveries were 78.3-110.6% with all RSDs ? 8.0%.The limit of quantification(LOQ)was calculated at 0.029-0.038 ng/m L.Concentrations of imidacloprid and metabolite 6-CNA in all of urine samples were determined,and the values were further corrected by urinary creatinine concentrations to eliminate individual differences.The results showed that imidacloprid and 6-CNA were detected in 100% of urine samples.The exposure level of urinary imidacloprid and 6-CNA for rural residents significantly increased after pesticide spraying,and urine samples in the 2d exhibited the highest concentration,and then the values gradually reduced with the extension of sampling time,but all exposure concentrations in rural residents were higher than those of urban control samples.The pesticide applicators and residents with different genders had almost the same exposure surrounding,and the concentration level in females was found higher than that in males.The concentrations of urinary imidacloprid and 6-CNA in the adolescents and elderly residents were higher than the other groups.For 3-6 years-old children,urinary concentrations from rural group were significantly higher than that of urban group,and the younger children tended to have higher exposure risk with the GM difference of 3.30-4.49 folds.People from different villages demonstrated diverse exposure levels with the GM difference of 1.13-3.28 folds.The varying rule of urinary metabolites among applicators at different time points were investigated.The results show that 242(ESI+ mode)and 170(ESI– mode)differential metabolites,which were significantly correlated with imidacloprid concentrations,were screened at 1d after spraying compared with those metabolites prior to application,and all differential metabolites exhibited the tendency of upregulation.Total of 17 metabolic pathways in vivo were influenced,including Glycerophospholipid metabolism,Pentose phosphate pathway,Glycine,serine and threonine metabolism,Arginine and proline metabolism,Alanine,aspartate and glutamate metabolism,Beta-Alanine metabolism,Galactose metabolism,Histidine metabolism,D-Arginine and D-ornithine metabolism,etc.,indicating that imidacloprid exposure may cause adverse effects towards routes of lipid metabolism,amino acid metabolism,energy metabolism and nucleic acid metabolism.In the urine samples at 3d and 7d after imidacloprid spraying,the level of only a few differential metabolites slightly recovered and showed a trend of downregulation,however,most of the differential metabolites had not yet recovered to the primary level,indicating that imidacloprid exposure may have potential long-term effects on human body.The oxidative stress effect of imidacloprid exposure was explored.Urinary concentrations of 8-OHd G increased for rural residents after spraying event in rural areas,and the content of 8-OHd G in the urines of rural children was higher than that of urban children,without reaching a significant level.Urine concentrations of imidacloprid and 6-CNA were significantly positively correlated with concentrations of 8-OHd G(with the correlation coefficient of 0.238-0.714),suggesting that imidacloprid exposure may cause potential oxidative damage to human body.In conclusion,rural populations in henan agricultural areas were exposed to higher level of imidacloprid,which may cause potential health risks. |
