ASSESSMENT OF POTENTIAL HUMAN HEALTH RISK FROM HEAVY METALS EXPOSURE VIA CONSUMPTION OF TEA (CAMELLIA SINENSIS) COLLECTED FROM THREE COUNTRIES

Beverage consumption is a common route of exposure to metals. Among the numerous types of beverages in the world, tea is most popular, right after the top-ranked water. Knowledge of metal content in tea and its effects on human health is therefore of great importance. To evaluate the health risks posed by carcinogenic and non-carcinogenic heavy metals in tea, this study determined the total and infusion concentrations of 9 metals including Ag, As, Ba, Cd, Cr, Cu, Pb, Se, and Zn in 45 types of black and green tea (Camellia sinensis) samples collected from three geographic locations (i.e., China, India, and USA). Kruskal-Wallis and Tukey-Kramer HSD tests showed that geographic locations had a significant (p < 0.05) influence on Ba, Cr, Pb, and Zn content in tea leaves, and on As, Ba, Cd, Cr, Pb, and Zn in tea infusion. The total Ba content in Chinese tea was significantly higher (p < 0.05) than those from India and the USA, while the total Cr content in Indian tea was significantly higher (p < 0.05) than products from the other two countries. As for general tea types, the total Cr and Cu in black tea were significantly higher (p < 0.05) than green tea, whereas in tea infusion only Cr in black tea was significantly higher (p < 0.05). Three infusions of each tea sample were further analyzed to evaluate the potential risks based on different drinking habits, which showed heavy metal contents were the highest in the first infusion and decreased gradually in subsequent infusions. Specifically, Cu and Zn concentrations in the second infusion were significantly lower (p < 0.05) than the first infusion and the concentrations of As, Ba, Cr, Cu, Se, and Zn in the third infusion were significantly lower (p < 0.05) than the first two infusions. Non-carcinogenic Hazard Quotient and Hazard Index were well below 1, with mean Hazard Quotient values in the order of As > Cr > Cu > Pb > Se > Zn > Cd > Ba > Ag, indicating consumption of tea infusion was not likely to create significant non-carcinogenic health risk. However, probabilistic estimation of carcinogenic risk of As exceeded the accepted risk level of 10^-5, showing that the carcinogenic risk of As exposure associated with tea consumption may be of concern. Avoiding the first infusion could reduce both non-carcinogenic and carcinogenic health risks from tea consumption.