The dietary significance of adventitious iron, zinc, copper and lead in domestically prepared food.

The uptake of iron, zinc, copper and lead by food cooked under domestic conditions in utensils made of different metals (cast iron, aluminium, plain and tinned copper) was investigated. It was found that the metal content of the food was generally related to the metal in immediate contact with the food during cooking. Daily dietary intake could vary from 11 to 6 mg of iron, 11 to 9 mg of zinc, 2 to 1 mg of copper and 0.4 to 0.1 mg of lead, depending on the cooking utensils used. Dietary intake of the metals was also related to sources and domestic practices regarding water supply. Consistent use of municipal water from a domestic hot water system could contribute a daily intake of 32 mg iron, 29 mg zinc and 12 mg copper. Rainwater stored in a galvanized iron tank could provide 23 mg of zinc per day when used for domestic purposes. The nutritional and toxicological significance of such adventitious sources of metals in the diet are discussed. The need to consider them when investigating the metal intake of individuals is stressed.