Establishment Of Internal Exposure Evaluation Method Of Neonicotinoids And The Exposure Risk Assessment

Objective: To develop a highly sensitive and accurate ultrahigh performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)method for simultaneous detection of 10 neonicotinoid pesticides(imidacloprid,acetamiprid,thiamethoxam,nitenpyram,thiacloprid,clothianidin,dinotefuran,imidaclothiz,flonicamid,sulfoxaflor)in human urine which are registrated in China.Then the developed method was used to detect and analyze the exposure level of neonicotinoid insecticides in adults and children in urban areas of Chongqing,and to evaluate the exposure risk.Methods: An UPLC-MS/MS method for detecting the exposure level of 10 neonicotinoid pesticides was developed by selecting electrospray ion source and multiple reaction monitoring mode,and optimizing mass spectrometry conditions including declustering voltage and collision voltage,chromatographic conditions including chromatography column,mobile phase,elution conditions and flow rate,and sample pretreatment conditions including enzymatic hydrolysis and solid phase extraction.A developed method was fully validated in terms of stability,linearity,limit of detection and quantitation,recovery rate,precision,and matrix effects.Then using the developed method,the exposure concentration of neonicotinoid pesticides in the urine samples of 25 adults aged 22 to 51 and 64 children aged 12 to 14 years in the urban areas of Chongqing was determined.The intake of neonicotinoid insecticides was estimated using the creatinine-corrected concentration.The single exposure risk was assessed comparing with the daily allowed intake.The cumulative exposure risk was assessed using hazard index method.Results:(1)The detection rate of 10 neonicotinoid pesticides in adults was 83.33-100%;the average concentration range was 2.97-14.42 μg/g creatinine;the median concentration range was 3.63-12.53 μg/g creatinine.The detection rate of 10 neonicotinoid pesticides in children was 56.25-100%;the average concentration range was 3.51-18.40 μg/g creatinine;the median concentration range was 2.99-9.87 μg/g creatinine.(2)The EDI average concentration range of 10 neonicotinoid pesticides in adults was 0.07-0.94 μg/kg;the median concentration range was 0.08-0.54 μg/kg.The EDI average concentration range of 10 neonicotinoid pesticides in children was 0.09-5.62 μg/kg;the median concentration range was 0.07-7.22 μg/kg.The maximum EDI value of thiameprid exceeded its ADI value,suggesting a potential exposure risk.(3)The adult HI range was 0.37-0.74;the median was 0.64 and the average was 0.61.The children HI range was 0.34-1.23;the median was 0.53;the average was 0.68.The maximum value of HI was 1.23,suggesting a potential risk of cumulative exposure for children.Conclusion: In this work,an UPLC-MS/MS method was developed for simultaneous analysis of exposure levels of 10 neonicotinoid pesticides in human urine.The stability,precision and accuracy of the method were all within acceptable standards.The method had low LOD and LOQ.The detection rate and the exposure concentration of neonicotinoid insecticides in adults and children in Chongqing showed that the exposure of neonicotinoid insecticides was very common,and the individual exposure was quite different.The single and cumulative exposure risk assessment of adults indicated that the exposure risk of neonicotinoid pesticides among adults were accepted in Chongqing at present.The results of the single exposure risk assessment of children showed that maximum EDI value of thiamethoxam exceeded the specified risk value,suggesting a potential exposure risk.The cumulative exposure risk results suggested that children might have health risks under the combined exposure of 10 neonicotinoid insecticides.