Study On Content Changes Of Heavy Metals In Tea Plantation Soil-Tea-Tea Infusion And Health Risk In Tea Infusion

Tea is an important perennial economic crop in China and it’s also one of the three famous non-alcoholic beverages in the world.It is favored by consumers because of its unique flavor and rich secondary metabolites.Jiangsu Province is the main producing area of famous green tea in China.The Dongting Biluochun and Yuhua Tea are well known in the world.In recent years,with the increasingly prominent food safety issues,the problems of heavy metal pollution in tea have also received widespread attention from consumers.In order to ensure the safety of tea plantation soil,tea leaves and tea infusion,various testing techniques and evaluation models were used to detect the heavy metal contents of tea plantation soil,tea and tea infusion,analyze the transfer rate of heavy metals in the soil-tea-tea infusion system and evaluate the health risks of heavy metals in tea infusion.In this paper,the soils and tea leaves samples were collected from 100 tea plantations in Jiangsu Province randomly.In order to study the spatial distribution characteristics,migration and health risk assessment of heavy metals in the soil-tea-tea infusion system,ICP-MS and ICP-OES were used to test 9 heavy metal elements(Zn,Cu,Pb,Cr,Cd,Mn,Hg,As,Ni)in soils,tea leaves and tea infusions.The USEPA health risk assessment model was used to evaluate potential health risk by drinking tea infusions.This study has practical significance for selection of tea plantations,improvement of tea plantation soil environment,etc.,and provides a theoretical reference for improving tea plantation soil,tea and tea beverage heavy metal content limit standards.The conclusion is as follows:(1)There was a significant spatial distribution of heavy metal content in tea plantation soils in Jiangsu Province,order of variation coefficient was Hg>Cd>Ni>Mn>Cu>Cr>Pb>Zn>As,ranging from 29.65 to 127.48%.The contents of Cd and Hg had strong variability.The average contents of Cu,Zn,As,Ni and Hg exceeded the soil background value of Jiangsu Province.The ratios exceeded the national standard of Cd,As,Hg and Cr in tea plantation soils were 3%,1%,3%,and 1%,respectively.The 92%of sameple points met the requirements of pollution-free tea plantations;The heavy metal contents of 91%tea leaves samples met the relevant requirements of the Ministry of Agriculture.As and Hg were not detected in the tea infusion samples.All in all,the quality of the tea plantation soils and tea leaves in Jiangsu Province were good.(2)The order of bioconcentration factors(BCF)of 11 heavy metal elements in tea tree was Mn>Cd>Ni>Cu>Zn>Hg>Pb>Cr>As,which showed strong enrichment ability for Mn and Cd.The order of heavy metal transition rates in tea leaves was Ni>Cr>Zn>Mn>Cu.The transition rate of Ni were 61.14%.If consumers take in Ni excessively,it may cause cancer risk to the human body,and should pay close attention to the content of Ni in tea leaves.In this study,the migration efficiency of heavy metals in the soil-tea infusion system was defined as the product of the BCF and the transition rate,and the provisional tolerable weekly intake(PTWI)was used to estimate the maximum limits in soil by producing healthy tea.The results were showed that in order to produce safe and healthy tea raw materials,relevant restrictions should be established for the Ni and Mn contents of tea plantation soil,and regular monitoring should be carried out.(3)The order of tea infusion’s EDI as follows:Mn>Zn>Ni>Cu>Cr;The order of THQ values was:Mn>Ni>Cu>Zn>Cr,and the mean value was less than 1,indicating that drinking tea infusion is less likely to cause potential harm to consumers’ health,but there were still some samples.The THQ value of Mn element is greater than 1,and the health risks caused by excessive Mn content in tea should be emphasized;The HI values of all samples ranged from 0.192 to 1.44,with a mean value of 0.447.The number of samples less than 1 accounted for 98%of the total number of samples,indicating that the overall production of tea in Jiangsu Province is good,but it is still necessary to pay attention to the content of Mn in tea leaves.