Characteristics Of Rare Earth Elements In Tea From Chinese Market And Their Exposure Risk Assessment

Objective:1.To analyze and compare the contents of 16 kinds of rare earth elements(REEs)in all categories of tea in Chinese market,to understand the composition status,distribution characteristics and patterns of rare earth elements in all categories of tea.To compare the contents of rare earth elements in tea from different provinces and to explore the relationships between the contents of rare earth elements in soil and the content of rare earth elements in local tea by tracing the origin of tea sold in China.2.To estimate the intake of rare earth elements through drinking tea for tea consumers in China,to compare the intake of rare earth elements through drinking tea of different regions and genders,and to evaluate the health risk of rare earth elements exposure in tea drinkers in China,in order to provide scientific basis for the management of rare earth elements in tea.Methods:According to the proportion of market sales,seven categories of tea samples were collected from 11 provinces of Jiangsu,Zhejiang,Anhui,Fujian,Jiangxi,Henan,Hubei,Hunan,Sichuan,Guizhou and Yunnan.The concentrations of 16 kinds of rare earth elements in all tea samples were detected.The mean,median,interquartile range and percentile were used to describe the average levels and variations of rare earth elements in all categories of tea.The Kruskal-wallis tests were used to compare the contents of rare earth elements in all categories of tea and the contents of rare earth elements in green tea produced by different provinces.Meanwhile,the compositions of rare earth elements in all categories of tea were described.The hierarchical cluster analysis was used to explore the distribution characteristics of 16 kinds of rare earth elements in different categories of tea sold in China,and the correlation between 16 kinds of rare earth elements in different categories of tea were also analyzed by Spearman rank correlation method.The intake of rare earth elements by drinking tea for Chinese tea consumers was estimated,in base of the content data of rare earth elements in tea obtained from the survey above,the data of tea consumption derived from the China National Food Consumption Survey 2014,and the leaching ratio of rare earth elements in different categories of tea reported by existing literatures.Also,the observed individual means(OIM)model,simple empirical distribution model and beta binomial normal distribution(BBN)model were used in the assessment.Furthermore,Mann-Whitney U tests were used to compare the intake of rare earth elements in tea for tea drinkers of different regions and genders.Finally,the hazard quotient(HQ)was utilized to judge that whether the risk to human health attributed to the intake of rare earth elements was acceptable for Chinese tea consumers.Results:1.The average contents of REE in oolong tea and dark tea were 2087.5(IQR:2675.6)?g/kg and 2186.6(IQR:1523.0)?g/kg,which were significantly higher than those in black tea 813.6(IQR:1081.5)?g/kg,green tea 853.7(IQR:901.5)?g/kg,white tea 776.8(IQR:372.7)?g/kg,flowering tea 566.7(IQR: 1123.0)?g/kg.Except for the rare earth element Eu,the contents of the other 15 rare earth elements in oolong tea and dark tea were significantly higher than that in black tea,green tea,flowering tea and white tea.The contents of light rare-earth elements(LREEs)in all categories of tea in the market were higher than that of heavy rare-earth elements(HREEs),and the proportions of LREEs and HREEs are about 70% and 30%.2.The clustering characteristics of rare earth elements in dark tea,black tea,white tea and flowering tea were similar,the rare earth elements La,Nd,Y were similar,the rare earth elements Eu,Gd,Pr and Tb were similar.The Ce,Sc and any other rare earth elements were not similar;The correlations among the rare earth elements in oolong tea,black tea,green tea and flowering tea were significant,and they were in all positive correlation.Among them,there was a good correlation between the rare earth elements in flowering tea and the correlation coefficient range was 0.674-0.985.3.The distribution patterns of REE in oolong tea,dark tea,black tea and white tea,as well as the distribution patterns of REE in the soil of mainland China,all showed that the enrichment degree of LREE was higher than that of HREE except Eu and the distribution curve was negative.In addition,the La-Eu curve was steep while the Eu-Lu curve was gentle,and the Eu showed obvious negative abnormally.4.The average contents of total rare earth elements in green tea of Jiangxi Province was 1621.2(IQR:1561.7)?g/kg,that in Guizhou Province was 1302.8(IQR:535.5)?g/kg,that in Jiangsu Province was 1177.3(IQR:689.4)?g/kg,which were significantly higher than that of other provinces.The average contents of total rare earth elements in green tea of Sichuan Province was 299.2(IQR:882.0)?g/kg,which was significantly lower than that of other provinces.The contents of rare earth elements in soil of origins of tea corresponded with that in green tea for most provinces.5.There was a significant difference in the daily intake of rare earth elements by drinking tea for adults in South and North of China,and the intake of southern population was higher than that of northern population.However,there was no difference in the daily intake of rare earth elements from tea between male and female adult tea drinkers in China.The average intake of rare earth elements through drinking tea for tea drinkers in China was 0.062?g/kg BW/d,and HQ was far less than 1(HQ=0.0012)so that the health risk was acceptable.The average intake of rare earth elements by diet for adult tea drinkers in China was 4.244?g/kg BW/d,which HQ was also less than 1(HQ=0.0824),and their health risk was also at an acceptable level.Conclusion:The contents of each REE(except for Eu)and total REE in in oolong tea and dark tea are both significantly higher than that in black tea,green tea,flowering tea and white tea.The clustering characteristics of REE in dark tea,black tea,white tea and flowering tea are similar.The correlation among REE in green tea,black tea,green tea and flowering tea is significant and positive,respectively.The REE distribution patterns of oolong tea,dark tea,black tea and white tea are similar with those of soil in mainland China.The REE contents of green tea in Jiangxi,Guizhou and Jiangsu province are all significantly higher than that in other provinces,the origins of tea.There is a significant difference in the intake of rare earth elements from tea for adult tea drinkers in South and North of China which the intake of southern population is higher than that of northern population,and health risk is acceptable for tea drinkers,regardless of southern population or northern population.The health risk caused rare earth element exposure by diet for adult tea drinkers in China is acceptable and low.