Residue And Dietary Risk Assessment Of Lambda-cyhalothrin In Pineapple And Kumquat

Lambda-cyhalothrin is a high efficiency,medium toxicity and broad-spectrum insecticides,which is used to prevent and control cockroaches on pineapple and aphids on kumquat.In order to formulate the maximum residue limits of lambda-cyhalothrin on kumquat and pineapple,guide the rational use of pesticide,and the safty of agricultural products.In this article,5%lambda-cyhalothrin microenulsion was used as a test agent.In2017,the dynamics of field digestion on kumquat and soil,and the final residue test on kumquat and pineapple were conducted,and dietary risk assessment of lambda-cyhalothrin on pineapples and kumquat was also evaluated.The results were as follows:A simple and rapid method for determination of lambda-cyhalothrin in pineapple,kumquat and soil sample was developed by gas chromatography-mass spectrometry.The samples were extacted with acetonitrile and ultrasonic cleaner,and centrifugally steamed,ethyl acetate dissolved,then detected in GS-MS.Limit of quantification in pineapples,kumquat and soil were 0.01 mg/kg.The average recoveries in pineapple pulp,pineapple,kumquat and soil were 76.5%⁹3.6%、63.2%⁹7.7%、80.1%¹07.1%、91.3%¹05.9%,respectively,and the relative standard deviations were 3.41%⁷.64%、1.22%⁴.05%、6.85%⁷.66%、1.59%³.27%.The sensitivity,accuracy and precision of the method well satisfied the essential rules of pesticide residue determination.The dynamics of residual digestion of 5%lambda-cyhalothrin microemulsions in kumquat and soil showed that:The original deposition amount of Guangxi kumquat was0.56 mg/kg,and the residual amount was less than 0.5 mg/kg within 10 days to 35 days.The digestion did not meet the first-order kinetic equation.The original deposition amount of Yunnan kumquat was 0.2 mg/kg.The kinetic equation for digestion was C=0.1322e^-0.132t.The half-life of lambda-cyhalothrin was 5.3d.R² was 0.9624.The 7 d digestion rate reached 75%.Dissipation dynamic of lambda-cyhalothrin in soil didn’t followed the first-order chemical kinetic equation.The original deposition amount of Guangxi soil was 0.37 mg/kg.The 35 d digestion rate reached 97.3%.The 35 d digestion rate of Guangdong soil reached 48.3%,and it could not fit the dynamic curve.The final residual amount of 5%lambda-cyhalothrin microemulsion on pineapple and kumquat was studied.5%lambda-cyhalothrin microemulsion on kumquats in six regions of Guangdong,Guangxi,Zhejiang,Yunnan,Fujian,and Sichuan were applied at 31.25⁴6.875 mg/kg with spraying 2 or 3 times at an interval of 7 days,As 7^th day,14^th day,and21^st day after application,the terminal residues of lambda-cyhalothrin were less than 0.73mg/kg.5%lambda-cyhalothrin microemulsion on pineapple in four regions of Guangdong,Guangxi,Hainan and Fujian were applied at 27⁴0.5 g a.i/ha with spraying 1 or 2 times at an interval of 7 days,As 5^th day,7^th day,14^th day,and 21^st day after application the terminal residues of lambda-cyhalothrin were less than method detection minimum concentration（0.01 mg/kg）.The long-term dietary intake risk of lambda-cyhalothrin on pineapple and kumquat was evaluated.Under good agricultural practice,the supervised trials median residue（STMR）of lambda-cyhalothrin in kumquat was 0.11 mg/kg,the national estimated daily intakes（NEDI）and national theoretical maximum daily intake（TMDI）of lambda-cyhalothrin were 0.5673 mg and 0.6537 mg,respectively,which was 45.02%and51.88%of acceptable daily intake（ADI）,respectively.The recommended maximum residue limit（MRL）of 2 mg/kg for lambda-cyhalothrin had no public health concern at the national level.The supervised trials median residue（STMR）of lambda-cyhalothrin was0.01 mg/kg,the national estimated daily intakes（NEDI）and national theoretical maximum daily intake（TMDI）of lambda-cyhalothrin were 0.5628 mg and 0.5632 mg,respectively,which was 44.67%and 44.70%of acceptable daily intake（ADI）,respectively.The recommended MRL of 0.02 mg/kg for lambda-cyhalothrin had no public health concern at the national level.The supervised trials median residue（STMR）of lambda-cyhalothrin in pineapple was 0.01 mg/kg,the national estimated daily intakes（NEDI）and national theoretical maximum daily intake（TMDI）of lambda-cyhalothrin were 0.5628 mg and0.5632 mg,respectively,which was 44.67%and 44.70%of acceptable daily intake（ADI）,respectively.The recommended MRL of 0.02 mg/kg for lambda-cyhalothrin had no public health concern at the national level.The above results suggest that recommending 2 mg/kg and 0.02 mg/kg as MRL values for lambda-cyhalothrin in kumquat and pineapple,respectively,has achieved an acceptable level of protection for Chinese consumers in terms of long-term dietary exposure risk.