Pollution Condition And Health Risk Assessment Of Lead And Cadmium In Tea Sold In Shijiazhuang

Objective:1.To evaluate the quality and safety of tea for sale in Shijiazhuang by determining the contents of lead and cadmium in tea and tea infusion and analyzing the differences of the contents among different tea varieties.2.Discuss the leaching regularity of lead and cadmium elements and the corresponding leaching rate after tea leaves are steeped for different times.3.The target hazard factor(THQ)method was used to evaluate the potential health risks of lead and cadmium in tea to human body.Methods: The samples were digested by wet digestion,and the contents of lead and cadmium in the samples were determined by graphite furnace atomic absorption spectrophotometer.Using the risk assessment model recommended by US Environmental Protection Agency(USEPA),the target hazard coefficient(THQ)was used to evaluate the potential health risks of lead and cadmium in tea and leaching solution to human body.Results:1.In this study,wet digestion and graphite furnace atomic absorption spectrophotometer were used for sample pretreatment and determination of lead and cadmium content,and the detection techniques were evaluated.The results show that this method has high precision and accuracy.The linear range of lead ion concentration was 0-0.08?g/ m L,the detection limit was0.53ng/ m L,and the recoveries were 98.12%-102.07%.The linear range of Cd ion concentration was 0-0.006?g/ m L,the detection limit was 0.047ng/ m L,and the recoveries were 87.70%-99.65%.The precision of atomic absorption spectrometry for the determination of lead and cadmium is high,with RSD range of 0.55%-2.70%.2.The lead content of tea leaves ranged from 1.22-3.49mg/kg,and the cadmium content ranged from 0.09-0.20mg/kg.The average lead content of different tea leaves was 1.71 mg/kg(scented tea),2.03 mg/kg(white tea),2.11mg/kg(green tea),1.76 mg/kg(black tea),2.53 mg/kg(dark green tea)and1.81 mg/kg(oolong tea),respectively.The median cadmium content was 0.17mg/kg(scented tea),0.16 mg/kg(white tea),0.19 mg/kg(green tea),0.14mg/kg(black tea),0.16 mg/kg(dark green tea)and 0.13 mg/kg(oolong tea),respectively.The contents of lead and cadmium in different tea varieties were different(H=30.162,P < 0.05;H=22.93,P < 0.05).3.In the process of tea brewing,the leaching rate of lead and cadmium increased first and then decreased with the extension of time,and the leaching rate reached the highest at 20 min.After 20 minutes of brewing,36 tea samples were randomly selected to determine the contents of lead and cadmium in the tea infusion.The lead content ranged from 0.93-1.75 mg/kg and the cadmium content ranged from 0.03-0.11mg/kg.The average leaching rate of lead in different tea leaves varied from 56.45%-69.37%,and the average leaching rate of cadmium in different tea leaves ranged from 34.03%-42.13%.The mean content of lead was 1.17 mg/kg(scented tea),1.34 mg/kg(white tea),1.23mg/kg(green tea),1.24 mg/kg(black tea),1.50 mg/kg(dark green tea)and1.10 mg/kg(oolong tea),respectively.The median contents of cadmium were0.06 mg/kg(scented tea),0.06 mg/kg(white tea),0.08 mg/kg(green tea),0.05mg/kg(black tea),0.07 mg/kg(dark green tea)and 0.04 mg/kg(oolong tea),respectively.There was no significant difference in the contents of lead and cadmium in leachate of different tea varieties(P > 0.05).4.The risk assessment of health hazards caused by lead and cadmium ingested by people through drinking tea showed that THQ(lead)of 81 tea samples ranged from 0.045 to 0.129,THQ(cadmium)ranged from 0.012 to0.026,and THQ(lead)of 36 tea extracts ranged from 0.034 to 0.065,and THQ(cadmium)ranged from 0.003 to 0.014.Conclusion: The contents of lead and cadmium in the commercially available tea and the leaching solution tested in this study meet the limited standards in China.The leaching rates of lead and cadmium in the brewing process of tea first increase and then decrease with the extension of time,and reach the maximum at 20 min.The leaching rates of both are relatively high and easy to be leached in the brewing process.The THQ values of lead and cadmium in tea and tea leaching solution were calculated to be less than 1,indicating that the lead and cadmium ingested by adults through tea drinking would not have adverse health effects on human body.