Background: Camellia sinensis infusion is the most widely consumed beverage in Nigerian. However, is heightened health concern regarding the occurrence of trace elements in food products considering their toxicity. Aim: To investigate the levels and health effects of trace metals in local and imported Camellia sinensis commercially sold in Nigeria. Methods: We assessed the speciation analysis of Cd, Cr, Cu, Mn, Ni, Pb, V, and Zn in 15 Camellia sinensis samples (11 green and 4 black teas) using the modified BCR sequential extraction method, and analyzed the sample fractions in quadruples using Microwave Plasma Atomic Emission Spectroscopy (MP-AES). Results: Trace metals were detected in all the samples investigated. The concentrations of Cd, Cr, Cu, Mn, Ni, Pb, V, and Zn in black tea ranged between 2.81-3.07, 1.87-2.60, 1.35-1.44, 37.04-48.32, 2.02-3.23, 1.02-1.22, 0.52-0.71, and 1.12-7.42 mg/kg, while concentrations in green tea ranged between 0.22-0.59, 0.06-0.18, 0.13-0.39, 4.55-14.71, 0.10-0.40, 0.06-0.16, 0.02-0.05, and 0.28-0.93 mg/kg respectively. Manganese (Mn) was found to be the most bioavailable trace metal, being largely bound in the exchangeable fraction of all the samples investigated, while Zn was the most predominant in the residual fractions. Other metals were distributed in varying concentrations across the four fractions. Vanadium recorded the lowest levels among the samples and was observed to be more bioavailable in black tea samples than in green tea products. Cd was observed to be more labile than Cr and Cu in the green tea samples. However, Cu was more bioavailable than Cd and Cr in black tea samples. The computed risk assessment code reveals potentially high – very high contamination risk associated with Mn exposure for all samples, no risk of V in green tea, medium – high risk of V in black tea, and medium to high risk for other trace metals. Conclusions: The risk of chronic trace metal exposure via ingestion pathway through consumption of Camellia sinensis is of concern to human health. High levels of Mn exposure may lead to neurological disorders, impotence or loss of libido. Increased aldosterone in the blood, renal dysfunction, retention of sodium and water in the body are some of the harmful effects of Cd exposure. Enforcement of the maximum contamination levels (MCLs) by food regulatory agencies is crucial to ensure that levels of human exposures to excess harmful and carcinogenic trace metals is significantly reduced.

Chemical speciation and contamination associated risks of trace metals in Camellia sinensis

254th National Meeting (2017)

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