Abstract:
Hot water infusions (HWI) of black tea manufactured using fresh bud and tender leaves of
Camellia sinensis L. (O) Kuntze ( Family: Theaceae) plant is a popular daily consumed
beverage in Sri Lanka. Some heavy metals are inherently present in black tea. Ingestion of
excessive amounts of these metals could cause health risk. Therefore, in this study,
Copper, Mercury, Lead and Arsenic content of BOPF grade black tea, sampled from major
agro-climatic elevations: low, mid and high grown in Sri Lanka and their HWI were
determined using Atomic Absorption Spectrophotometer. The serum metal contents were
assessed (using AAS) in rats orally administered with different doses of black tea HWI of
high grown (human equivalent of 1.5, 3 and 12 cups per day), high dose (equivalent of 12
cups) of mid and low grown or water (control), thrice a day for consecutive 90 days.
During the treatment, rats were daily observed for overt signs of toxicity and at the end of
the treatment on chronic toxicity (renal and hepato-toxicity) were assessed. The total
contents of heavy metals in black tea differ according to the agro-climatic elevations: Cu,
27.3 – 75.6 mg/kg; Hg, 0.01 – 0.026 mg/kg; Pb, 0.02 – 0.065 mg/kg and As, 0.003 – 0.006
mg/kg. The percent releases from black tea to their infusions were: Cu, 86 ± 8 %; Hg, 78 ±
6 %; Pb, 42 ± 3 % and As, 56 ± 9 %. Compared to control, blood serum metal contents
were significantly (p < 0.05) and dose- dependently increased by black tea tested with high
grown: Cu, 1.14 – 1.93 #g/dl; Hg, 0.10 – 0.19 #g/dl and Pb, 3.78 – 6.84 #g/dl. In contrast,
As content was not altered (0.05 – 0.07 #g/dl). All metals tested were below the
permissible limit prescribed by FAO. Further, there were no signs of toxicity. Therefore,
daily consumption of even 12 cups of Sri Lankan black tea may not produce any health
risk.
