长期饮用砖茶人群铅、硒、砷及汞暴露水平

Exposure levels of lead,selenium,arsenic and mercury in brick-teas from main producing areas in China

目的了解中国茶叶主产区砖茶中铅(Pb)、硒(Se)、砷(As)和汞(Hg)等元素的含量,评估长期饮用砖茶人群Pb、Se、As和Hg元素的暴露水平。方法在内蒙古、甘肃、新疆、青海、四川、西藏和云南等习惯饮用砖茶的地区收集了31份不同产区的砖茶样品,用等离子发射光谱法测定砖茶Pb含量,氢化物发生原子荧光光谱法测定砖茶中As、Se和Hg含量并进行评价。结果砖茶中Pb、Se、As及Hg的含量均值分别为6.232、0.219、0.524和0.0215 mg/kg。依据GB 2762—2012中茶叶Pb的限量标准评价,砖茶Pb超标现象较为突出,不同产地砖茶Pb含量差异明显,含量最低为云南所产沱茶和普洱茶,平均含量为1.337 mg/kg,浙江所产茯砖Pb含量亦较低,为4.303 mg/kg,符合限量标准,Pb含量最高为四川所产康砖,含量达9.998 mg/kg。所测砖茶As、Hg含量均符合NY 659—2003中规定的限量标准。采用联合国粮农组织和世界卫生组织食品添加剂联合专家委员会(JECFA)暂定的每周污染物耐受摄入量(PTWI)评价表明,长期饮用砖茶人群通过砖茶平均摄入的Pb、As和Hg对PTWI的贡献率分别为13.63%、1.71%和0.29%,均在安全范围之内;通过砖茶每日摄入的Se为0.188μg,对人群硒膳食推荐摄入量(RNI)的贡献率仅为0.38%。结论中国主要砖茶存在Pb超标现象,长期饮用砖茶人群As、Hg处于低暴露水平,饮用砖茶对补充体内Se的生理需要作用有限。

Objective To study the levels of Pb,Se,As and Hg in brick-teas from main producing areas in China and evaluate the safety. Methods A total of 31 samples of brick tea from seven provinces where minority nationalities were accustomed to drinking a large quantity of brick tea were collected, Pb concentrations were determined by inductively coupled plasma-mass spectrometry,and concentrations of As,Se,Hg were detected by hydride generation atomic fluorescence spectrometry. The data were analyzed by SPSS 22. 0 software. Results The average lead levels in brick tea was 6. 232 mg/kg,which exceeded the limit standard of GB 2762—2012. There was a great difference of Pbconcentrations among the various kinds of brick tea producing in different provinces,and the lower Pb concentrations detected in Tuo tea and Puerh tea producing in Yunnan Province,was 1. 337 mg/kg,and the highest determined in Kang brick producing in Sichuan Province,was 9. 998 mg/kg. In addition,the concentrations of As and Hg were all below the limit standard of NY 659—2003. For people accustomed to drinking brick tea for a long term, the average intake amounts of Pb, As, Hg through brick tea contributed 13. 63%,1. 71% and 0. 29% to dietary Pb,As,Hg of the provisional tolerable weekly intake（ PTWI） recommended by Joint FAO/WHO Expert Committee of Food Additives（ JECFA） which was in safe range. Otherwise,the daily selenium intake through brick tea was 0. 188 μg,which contributed 0. 38% to the selenium recommended nutrient intake（ RNI） by Chinese Nutrition Society. Conclusion Excessive levels of lead in the brick tea is prominent. As,Hg and Se in brick tea are in low exposure level.