Heavy metals: leaching from glazed surfaces of tea mugs

Heavy metals (zinc, lead, cadmium, iron, chromium, copper, manganese, nickel and cobalt) were found to leach from the glazed surfaces of tea mugs collected from 13 different pottery units of Khurja (U.P.) and one each from Ghaziabad (U.P.) and Calcutta (West Bengal) determined under different conditions. The leachates used were: tea at 80°C, orange juice at room temperature and 4% acetic acid at room temperature, 40°C and 60°C, respectively. The volume (capacity) of mugs ranged between 200 and 250 ml. The duration for leaching was 24 h in each case without stirring. The concentrations of metals leached in tea at 80°C were found in the range (in μg/l): Zn, 236–730; Fe, 98–925; Cr, 62–119; Cu, 63–299; Mn, 710–2670; and Ni, 70–80 μg/l. The concentrations of metals leached in orange juice at room temperature were in the range (in μg/l): Zn, 393–1262; Cd, 25–349; Fe, 122–342; Cr, 66–945; Cu, 135–853; Mn, 166–424; and Ni, 70–134 μg/l. The concentrations of heavy metals extracted by 4% acetic acid at room temperature were found in the range (in μg/l): Zn, 18–192; Fe, 143–372; Cu, 51–190; and Mn, 0–48 μg/l; at 40°C (in μg/l): Zn, 118–837; Fe, 124–639; Cu, 230–722; and Mn, 30–63 μg/l and at 60°: Zn, 33–900; Fe, 83–576; Cu, 90–685; and Mn, 43–778 μg/l, respectively.