Bioavailability Of Arsenic In Leafy Vegetables

Arsenic(As)is the most closely monitored metals in China and known as non-threshold carcinogen.However,increasing arsenic was released into farmland soil with the rapid development of industrialization and urbanization,which could be easily uptake by crop plants such as leafy vegetables,and then enter human body via food chain.Leafy vegetables can pose potential risks associated to human health because of its higher contribution to the total daily intake of As.Oral bioavailability refers to the fraction of As in the vegetables matrix that reaches the systemic circulation following ingestion,which is an important factor for human health risk assessment.In vivo assays can be used as an accurately assess As bioavailability.However,in vivo assays were considered the laborious,time-consuming,and expensive.Therefore,it's urgent to establish in vitro method for estimating As bioavailability in leaf vegetable to overcome the time and expense limitations of in vivo assays.In the current study,five representative in vitro models,including the RIVM(Rijksinstituut Voor Volksgezondheid Enmilieu),SBRC(Solubility Bioavailability Research Consortium),DIN(Deutsches Institut fur Normung e.V.),IVG(In Vitro Gastrointestinal),and PBET(Physiologically Based Extraction Test)were selected to evaluate bioaccessibility of As in leafy vegetables,and compared variation among them.Meanwhile,to find the most accurate in vitro models evaluate bioaccessibility of As in leafy vegetables,a rat model assay was conducted to evaluate bioavailability of As in leafy vegetables,the correlation between As bioaccessibility in leafy vegetables among five representative in vitro models and As bioavailability assessed by in vivo assay was analyzed,and then a new IVIVC model(in vivo-in vitro correlation)was established to predict bioavailability of As in pakchoi cultivars and its human health risk.The results showed that:1.In the gastric phase,As bioaccessibility in leafy vegetables ranged from 8.0%to 64.2%,mean values was 28.8%,in this phase,the orders of As bioaccessibility in leafy vegetables was RIVM>SBRC>DIN?PBET>IVG.Meanwhile,As bioaccessibility in leafy vegetables ranged from 7.2%to 61.7%in gastrointestinal phase,its mean value was 30.8%,and the orders of As bioaccessibility in leafy vegetables in this phase was RIVM>SBRC>PBET>IVG>DIN.Significant difference in As bioaccessibility of leafy vegetables assessed by five representative in vitro models was observed.This is mainly due to the difference of pH value,the extraction reagent,extraction time and the ratio of solid to liquid in these different in vitro models.Thus,it's important to select a suitable and accurate in vitro model to evaluate bioaccessibility of As in leafy vegetables.2.Arsenic-RBA in leafy vegetables was ranged from 12.1%to 54.8%,which was estimated by a rat assay.The significant variation of Arsenic-RBA in leaf vegetables was related to total As content and species,and other composition in vegetables.To establish a new IVIVC model to predict As bioavailability in leafy vegetables,the correlation between As bioaccessibility in leafy vegetables based on five representative in vitro models and As bioavailability assessed by in vivo assay was analyzed.The result showed PBET was validated as the most suitable model in this study to determine the relative bioavailability of arsenic in leafy vegetables.Thus,a new IVIVC model As-RBA = 2.0970 + 0.9838(PBET-IP)was established.3.A new IVIVC model was used to predict bioavailability of arsenic in pakchoi among six selected cultivars.Then human risk assessment of As in pakchoi based on bioavailability of As and As concentration was analyzed,the results showed that higher THQ value was obtained from method based on As concentration than that of base on bioavailability of As.The bioavailability of arsenic was used as the exposure dose to evaluate the human health risk of leafy vegetables,which was closer to the real absorption of arsenic in vegetables than the total method,and the evaluation method was more accurate.After the evaluation of the arsenic bioavailability method,the arsenic health risk assessment of some Chinese cabbage still exceeded the threshold.Therefore,it is necessary to pay attention to the cultivation of arsenic in the arsenic contaminated area by planting structural adjustment or variety replacement.