Potential Health Risk Assessment of Heavy Metals via Consumption of Green, Black and Herbal Tea Marketed in Northwestern Nigeria

Abstract

Tea has become most popular non-alcoholic beverage consumed by people of different age group worldwide and regarded beneficial for public health. However, the acidophilic characteristic of tea plant and its potential tendency to bio-accumulate metals including heavy metals from the environment, is of serious concern to consumers and health authorities. Concentration of Cd, Fe, Cu, Ni, As and Pb in a total of 90 tea samples representing three most consumed tea varieties (green tea, black tea and herbal tea) from Northwestern Nigeria, were analyzed using microwave plasma  atomic emission spectroscopy (MP-AES). The results indicated that the analyzed metals were detected in the three tea varieties except arsenic in green tea samples and the study observed significant percentage of metal transfer rate from tea leaves to infusion. The Heavy metal concentration varied among the different tea varieties in the study and with highest concentration of Cd and Pb in green tea while Fe, Cu, As and Ni in black tea infusions. The EDI values for all the metals in all the brands of green, black, herbal tea infusion in this study were below their corresponding RfD values. The THQ values of each metal through the consumption of green, black and herbal tea infusions were all below 1. However, some individual brands of green tea infusion (GT8 and GT10) have HI greater than 1 and this is an indication of some potential non-carcinogenic health risk to habitual green tea infusion in the study area. The estimated carcinogenic risk (ECR) values for Cd in green and black tea infusions as well as As in black tea infusion were at the upper margin of 10-4, suggesting possible carcinogenic risk to habitual tea consumers in the study area.