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The exposure risk through the dietary, drinking water and inhalation routes of eight pesticides, namely propoxur, chlorfenapyr, dichlorvos, trichlorfon, malathion, fenitrothion, indoxacarb and emamectin benzoate to birds was evaluated using the exposure models including “guidelines on environmental risk assessment for pesticide registration—part 3: birds”, SIP model and STIR model. The registration of crops for pesticides and their application information were obtained from “China Pesticide Information Network”. The avian toxicological data were obtained from United States Environmental Protection Agency, European Food Safety Authority, PubChem and Pesticide Properties Database. Results showed that, through the dietary route, the primary acute risk of propoxur to birds was unacceptable. The primary long-term risk of propoxur to birds was acceptable. The primary acute, short-term and long-term risks of dichlorvos, chlorfenapyr, trichlorfon and fenitrothion to birds were unacceptable. The primary short-term and long-term risks of malathion to birds were unacceptable. The primary acute, short-term and long-term risks of indoxacarb and emamectin benzoate to birds were acceptable. Through the drinking water route, the acute and chronic risks of chlorfenapyr and indoxacarb to birds were not of concern, and the risks of the other 6 pesticides need to be concerned. Through the inhalation route, only the volatilized inhalation risk of dichlorvos to birds need to be concerned, and the droplet inhalation and volatile inhalation risks of the other 7 pesticides to birds are not of concern. In summary, among the 8 pesticides commonly used in forestry, only the risk of indoxacarb to birds was acceptable or not of conceren through all of the dietary, drinking water and inhalation routes. The risks of the other 7 pesticides to bird needed to be concerned. Our assessment could provide the references for the safe application of those 8 pesticides in the economic forest and proposals for the improvement of methods to assess the risk of pesticide to birds in China. However, only primary risk assessment was performed in this study, leading to conserved results. More accurate assessment results could be obtained by carrying out investigation and toxicology studies. [ABSTRACT FROM AUTHOR]

To investigate the influence of four types of lactic acid bacteria (LAB) on the degradation of malathion enantiomers, which included Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, Lactobacillus plantarum subsp. plantarum, and Lactobacillus casei, the separation of malathion enantiomers and the enantioselective degradation were studied using an CHIRALCEL OD-H column and HPLC. Malathion in MRS medium were extracted by acetonitrile and purified with florisil SPE column. The results showed that the LABs reproduced faster in first 24 h and peaked at 36 h, then it remained steady. The pH value of medium with LABs decreased from 7 to 5 after 24 h and kept stable afterwards, while the pH value of control group remained 7. The half-lives of (±)-malathion ranged from 5.4-6.5 d and 5.1-6.3 d, respectively, and no distinct difference was observed which indicated that the degradation of malathion was not influenced by LABs. [ABSTRACT FROM AUTHOR]

The residues of malathion in Cucurbita pepo. was determined using gas chromatography equipped with flame photometric detector (GC-FPD). The standard residue trials of malathion in C. pepo were carried out in Hunan, Shandong, Beijing, Anhui, Shanxi and Heilongjiang in 2016. The dietary intake risk assessment to different populations and different foods based on the residual data of malathion was conducted. The C. pepo samples were extracted with acetonitrile, determined by GCFPD after the displacement of acetonitrile with acetone. With the fortified level from 0.02 to 8.0 mg/kg in C. pepo samples, the recoveries ranged from 88% to 109% with the relative standard deviations (RSD) of 5%. The limit of quantitation (LOQ) of the method was 0.02 mg/kg. The dissipation dynamic test results obtained from Hunan and Shandong showed that malathion was easily degradable, and the half-life of malathion was 2.74-4.65 days. The final residues in C. pepo from six provinces were < 0.02- 0.049 mg/kg with interval 3, 5 and 7 days after last applied. The dietary risk assessment results showed that the national estimated daily intake (NEDI) was between 0.115-0.207 μg/(kg bw·d) and the risk quotients (RQ) were between 0.000 4-0.000 7 for different populations in China. The total dietary exposure risk assessment results indicated that the NEDI of malathion in all kinds of foods was 82.251 μg/(kg bw·d), and the RQ was 0.275 1, which demonstrated that malathion applied to C. pepo had low risk. The maximum residue limit (MRL) of malathion in C. pepo is recommended to be 0.1 mg/kg in China, which would ensured dietary intake safety of C. pepo. [ABSTRACT FROM AUTHOR]

The traditional pesticide residues detection methods had the disadvantages of complex sample preparation, expensive apparatus and high cost.For developing a rapid analysis detection method of pesticide residues, we investigated a surface enhanced Raman spectroscopy (SERS) method coupled with colloidal gold for detection and characterization malathion residues in Chinese cabbage.Chemometric method was used to establish a rapid detection model of malathion pesticide residues in Chinese cabbage.A 200 mg/L standard solution was prepared by dissolving malathion power in acetonitrile.The standard solution was serially diluted with ultrapure water to prepare working solutions of 100, 50, 20, 15, 10, 5, 2, 1 and 0.5 mg/L.Fresh Chinese cabbages were collected from the agronomy experimental base of Jiangxi Agricultural University in June 2015.The Chinese cabbages were used to prepare samples as follows.50 g Chinese cabbages were weighed and transferred on a plastic wrap.76 Chinese cabbage samples were manufactured by spraying different concentration standard solution with a sprinkling can, and each concentration has two parallel samples.Then the 76 samples were homogenized separately by pulverizer.After that, the sample preparation steps were implemented for both SERS collection and GC MS measurement as follows.1) 10 g homogenized chinese cabbage sample, 1 g anhydrous sodium acetate, 5 g sodium chloride and 10 mL acetonitrile were blended in a centrifuge tube of 50 mL, and the centrifuge tube was vibrated for 1 min with a vortex mixer.A homogeneous solution was obtained and then separated for 5 min at a speed of 4 200 rpm on the centrifuge, and a yellow supernatant was acquired.2) 2 mL of the supernatant was injected to a centrifuge tube of 15 mL containing anhydrous Magnesium sulfate, PSA, graphitized carbon and C18 for removing the effect of protein, fat, carbohydrates and other substances in Chinese cabbage.The centrifuge tube was blended for 1 min and then centrifuged for 5 min at a speed of 4 200 r/min.Then, the colourless supernatant was filtered.The filtrate was used directly for SERS measurement in the Optics Electrics Application of Biomaterials Lab.3) 1 mL of the filtrate was transferred into a 10 mL centrifuge tube and condensed with a termovap sample concentrator at 60 ℃ until the solvent absolutely evaporated.4) The concentrated pesticide was diluted with 1 mL ethyl acetate and shaken for a moment.Then the eluted solution was transferred into a vial and used to measure its actual value by GC MS in Jiangxi Entry Exit Inspection and Quarantine technology center.Then three methods as SNV, MSC and Normalization were used to optimize the original Raman spectra signals, and the PLS models of malathion pesticide residues in Chinese cabbage were established .The limit of detection (LOD) can reach the level of 1.082 mg/L by SERS method, and the concentration can meet the tolerance levels for malathion pesticide residues in chinese cabbage.The model predictive performance used normalization preprocessing method was optimal.The correlation coefficient of the calibration samples model(Rc) was 0.983 2, RMSECV was 1.78 mg/L, the correlation coefficient of prediction model (Rp) was 0.973 2, and RMSEP was 2.37 mg/L.The model results of the higher Rp value and the lower RMSEP value indicated that the method of SERS could accurately predict the malathion pesticide residues in Chinese cabbage.The five unknown concentration samples were prepared to verify the accuracy of the prediction models.The absolute values of relative deviation were calculated to be between 0.70%-9.84%.The predict recoveries were calculated to be between 99.30%-109.84%.These indicated that the SERS method was receivable and credible for rapid detection of malathion pesticide residues in Chinese cabbage.The t value was 1.589, less than t0.05,4=2.776. The results of t test demonstrated that the difference between SERS and GC MS was not significant. This study demonstrates that SERS is capable of detecting and identifying malathion pesticide residues in Chinese cabbage quickly and accurately. [ABSTRACT FROM AUTHOR]