Uptake of lead by vegetable foodstuffs during cooking.

Uptake of Pb by foodstuffs during cooking has been identified as an additional potential source of human exposure to Pb. Vegetables and rice cooked in water containing Pb may adsorb up to 80% of the Pb in the water. The amount of Pb adsorbed was dependent upon the concentration of Pb in the water, type of vegetable, water hardness, salting of the water, duration of cooking and the available surface-area of the vegetables. Substantial deposition of Pb also occurred on the surfaces of the saucepan itself (Al greater than enamel greater than Teflon), with subsequent desorption under certain cooking conditions. During tea-making, the concentration of Pb in water was reduced by 30-40% due to adsorption of Pb by the tea-bags. The dietary significance of the adsorption of Pb by foodstuffs during cooking as an additional source of human Pb uptake is assessed.