Abstract
Tea (Camellia sinensis (L.) Kuntze) is among the most widely consumed non-alcoholic beverages. It is a rich source of essential dietary elements mainly potassium and manganese. Tea may also contain toxic metals such as cadmium and lead which pose a threat to human health because of their toxicity. Twenty samples of commercial black tea in Kampala city were randomly obtained and analysed for potassium, sodium, aluminium, arsenic, cadmium, chromium, copper, iron, mercury, manganese, nickel, lead and zinc using Atomic Absorption Spectrophotometry. Human health risks due to exposure to toxic elements from daily consumption of tea were determined using incremental lifetime cancer risk and non-cancer hazard quotient. Metal contents of black tea sold in Kampala were below international regulatory limits. The estimated daily intake of the elements in two grams of black tea was below the recommended values. Hazard quotient and hazard index were within acceptable range. Total cancer risk levels for all the teas were also within United States Environmental Protection Agency (USEPA) acceptable range. Daily consumption of one cup containing two grams of black tea over a lifetime will promote consumer overall health and wellbeing.
Highlights
IntroductionEnvironmental pollution may cause the occurrence of excessive amounts of heavy metals in plants and food products
ILCR = (C × IR × EF × ED × CSF)/ (BWa × ATc) where: HQ = hazard quotient; C = average concentration of heavy metals (HM) in black tea; IR = ingestion rate, the amount of black tea consumed per unit time; EF = exposure frequency (365 days/year); ED = exposure duration of 30 years; RfD = chronic oral reference dose; BWa = average adult body weight (70 kg); ATn = averaging time, non-carcinogens (ED ×365 days/year = 10950 days); ILCR = incremental lifetime cancer risk; CSF = cancer slope factor-1; ATc is the averaging time, carcinogens (62.3 years × 365 days/year = 22,739.5 days) (USEPA, 1989)
The observed concentrations of potassium are a result of specific incorporation of potassium within a binding ligand of the tea leaves (Brzezicha-Cirocka, Grembecka, & Szefer, 2016)
Summary
Environmental pollution may cause the occurrence of excessive amounts of heavy metals in plants and food products. These elements have been found in drinking water (Bamuwamye et al, 2017), tea leaves and brewed black tea infusions (Lasheen, Awwad, El-khalafawy, & Abdel-Rassoul, 2008; Schwalfenberg, Genuis, & Rodushkin, 2013). Despite the fact that many studies reported high concentration of toxic and essential elements in commercial teas (Karak & Bhagat, 2010; Mohagheghian et al, 2015; Soliman, 2016; Karak et al, 2017), there is limited data on the metal composition of teas sold to the public in Uganda. The human health risks posed by these metals from daily consumption of black tea were computed
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