| Pesticide residues will go directly or indirectly across the bio-membrane through a variety of ways and cause harmful impact to organisms. Currently, there are two different biological absorption model, one is in-vivo absorption model and the other is in-vitro absorption model. Artificial membranes and absorbent tissue are both in-vitro absorption models. In-vivo experiment needs long time and high cost. In-vitro model is relatively simple compared to in-vivo model. Parallel Artificial Membrane Permeability Assay(PAMPA) is a more economical method than the traditional biological methods, and it is also high-efficient and convenient. The study was to construct a PAMPA technology which can simulate the membrane of different organizations. The main purpose is to research the membrane absorption of different kinds of pesticides which neonicotinoid, organic phosphorus, pyrethroids, triazine and other commonly used pesticides are included, and to assess the relationship of biofilm absorption and physicochemical properties of these pesticides, and finally carried out the dietary health risk assessment of pesticide residues in apple.By adjusting the biofilm components and proportions, we builded a PAMPA biofilm technology which can simulate gastric and intestinal absorption, then tested apparent permeability (Pa) and effective permeability (Pe, effective permeability of the membrane considered the interception) of 51 pesticides, then predicted the body absorption through permeability of different pesticides, and assessed the relative absorption importance between stomach and intestinal tissues. Analysised the correlation between permeability and other basic properties (molecular weight, molecular size, molecular polarity, octanol-water partition coefficient, solubility, melting point, boiling point). The results showed that there are no correlation between permeability and basic properties(R2=0.217). Then analysised the correlation between BCF and other basic properties. When permeability was not considered, BCF was related to Kow and solubility(R2=0.702), and if considered the permeability, Log BCF=0.23Log(Kow)-0.416Log(solubility)+0.088Log(intestinal Pa)+0.193Log(gastric Pa)+2.66 9(R2=0.755,n=51),LogBCF=0.166Log(Kow)-0.41 Log(solubility)-0.523Log(intestinalPe)+0.67 1 Log(gastric Pe)+2.222(R2=0.760, n=51). The results indicated that it can more effectively predict the BCF with the permeability.Finally, we tested the pesticide residues in totally 16 apple samples which was bought in Agricultural Market and large Supermarkets and then carried out the chronic dietary intake risk assessment. The results show that 15 pesticides include iprodione,azoxystrobin, methyl ethyl disulfoton, aldrin, fenthion, epoxy heptyl alkyl chloride, trans-chlordane, cis-chlordane, trans-9 chloride, cis-9 chloride, endrin, endrin aldehyde and endrin ketone,4,4-DDD, endosulfan sulfate were not detected. The average concentration of pesticides was between 55.07?g/kg?1077.77?g/kg. The %ADI value of each pesticide without considering the biological uptake is less than 100%, which indicates that the risk of chronic dietary intake of pesticides is acceptable. When considering bio-absorption,%ADI value of 25 kinds of pesticides were all less than 5%, which indicated that traditional risk assessment overestimate the risk of pesticides. The cumulative risk index E%ADI was 195.34% without considering biological uptake, and the ?%ADI was 54.064% when considering biological uptake which was between 5% and 100 between% indicated that the cumulative risk of pesticides is acceptable but needs attention. |
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