Study On The Methods For The Determination Of Emerging Mycotoxins And Dietary Exposure Assessment In China

Alternaria are ubiquitous saprophytes and may cause spoilage of fruits and vegetables during refrigerated transport and storage,is the most frequently-detected Fungus contaminant in food worldwide.Alternaria is able to produce more than 70 toxic secondary metabolites,called alternaria mycotoxins?ATs?,which include tenuazonic acid?TeA?alternariol?AOH?,altenuene?ALT?,alternariol monomethyl ether?AME?and tentoxin?TEN?.Tenuazonic acid?TeA?has acute toxic effects on various mammals reviewed by Ostry and the European Food Safety Authority?EFSA?.The Enniatins and Beauvericin are a group of cyclic hexadepsipeptides consisting of alternating hydroxy acid and N-methylamino acid residues that have been discovered in a strain of Fusarium oxysporum,parasitic to maize,wheat,rice and other important commodities.There is strong evidence that emerging mycotoxins are mutagenic,cytotoxic and genotoxic.To satisfy the need of the determination of emerging mycotoxins in food matrices,a sensitive and reliable method was developed in this study.the occurrence of emerging mycotoxins in several typical kinds of foods and the research of dietary exposure assessment.Total diet study is designed to measure the average amount of emerging mycotoxins,whose data is necessary to assess whether the emerging mycotoxins pose a risk to health.Firstly,a ultra-high performance liquid chromatography coupled with tandem triple quadrupole mass spectrometry?UPLC-MS/MS?method for the determination of emerging mycotoxins in 12 food matrices has been developed.Isotope-labeled internal standards were used for accurate quantification.The food samples were ultrasonically extracted with extraction solution(450 mL acetonitrile and 100 mL methanol in 450 mL of 0.05 mol L^-1phosphate buffer?ammonium dihydrogen phosphate,pH 3.0?)and then purified using Oasis HLB SPE columns.The purified extracts were dried under nitrogen and reconstructed in proper sample solvent.The samples were detected by UPLC-MS/MS and quantified by internal sa mple solvent.All mycotoxins exhibited good linearity over the working range except BEA whose regression coefficient?r?of calibration curves was0.9778,and the others were ranged from 0.9902 to 0.9982.The limits of detection?LODs?and limits of quantitation?LOQs?ranged from 0.0021 to 0.27 ng mL^-1 and from 0.007 to0.95 ng mL^-1,respectively.The recoveries were ranged from 60.6%to 175.9%,with relative standard deviations?RSDs?less than 12.3%.This method is reliable and sensitive for the determination of emerging mycotoxins in diet samples.Secondly,the developed and validated method was used to measure the presence of emerging mycotoxins in 12 different food matrices from 16 finished provinces of 6^th China total diet study.The total detection rate of them was 80.2%,with significant differences among food matrices,where cereals had the highest detection rate at 100%,followed by legumes,potatoes,eggs,aquatic products,dairy products and alcohol beverages.Beverages and water had the lowest detection,which is detected in only 2 samples.AME,TeA,TEN,ENNB and ENNB₁ contamination were more serious at north region rather than south region,whereas ENNA and ENNA₁ were on the opposite side.ALT was similarity between north and south.AOH was detected in only 1 sample.In this study,the emerging mycotoxins were in lower concentration rather than other determination,except TeA.The aquatic foods in JiangXi province had the highest TeA levels at 934.86?g/kg,which need to pay more attention.Thirdly,this study was working on the dietary exposures of adult males to emerging mycotoxin combined with food consumption data in the 6^th China total diet study.The national average daily dietary exposure to emerging mycotoxins in China was 40.54ng/kg bw/d.There were significant regional differences,with NeiMengGu and HeNan province having a high exposure that was 99.42 ng/kg bw/d and 91.35 ng/kg bw/d,respectively.GuangXi and HuNan province having the exposure less than 10 ng/kg bw/d.The threshold of toxicological concern?TTC?approach was used to assess the relative level of concern of emerging mycotoxins for human health.The TTC value of TEN and TeA were all under1500 ng/kg bw/d,that the exposure estimates were unlikely to be a human health concern.The TTC value of AME,AOH and ALT were all higher than 2.5 ng/kg bw/d,that the dietary intake of them were in a potential hazard in China.The exposure of general population to BEA all low at less than 50 ng/kg bw/d except in BeiJing,while ENNs all low at less than 30 ng/kg bw/d.Overall,cereals is the primary source of exposure to emerging mycotoxins,followed by beverages and water.TeA had the highest contribution to the total exposure,accounting for 46.2%,with ENNA and ENNA₁ combining to contribute approximately 0.1%.To sum up,this study developed a UPLC-MS/MS method for emerging mycotoxins in 12 different food categories samples and working on the dietary exposures of adult males to emerging mycotoxin in the 6^th China total diet study.Based on the determination results of the TDS samples from 16 provinces,the threshold of toxicological concern?TTC?approach was used to assess the relative level of concern of emerging mycotoxins for human health.This revealed that the dietary intake of emerging mycotoxins was a potential health hazard in China.