EXTRACTION OF LEAD, CADMIUM AND ZINC FROM OVERGLAZE DECORATIONS ON CERAMIC DINNER-WARE BY ACIDIC AND BASIC FOOD SUBSTANCES

Dinnerware decorated with overglaze designs can release toxic metals i nto food substances in amounts high enough to constitute health hazard s. When dishes made in the US before 1970 were filled with 4% acetic a cid for 24 h, lead concentrations of up to 610 mu g/ml and cadmium con centrations of up to 15 mu g/ml were measured. Acetic acid leachates f rom more than half the dishes tested for lead (78 of 149) contained le vels exceeding the US Food and Drug Administration (FDA) allowable con centration of 3.0 mu g/ml. One-fourth of dishes tested for cadmium (26 of 98) exceeded the FDA limit of 0.5 mu g/ml. High concentrations of lead, cadmium and zinc were also released into 1% solutions of citric and lactic acids. Significant amounts of these metals were extracted b y basic solutions of sodium citrate and sodium tripolyphosphate as wel l as by commercial food substances including sauerkraut juice, pickle juice, orange juice: and low-lactose milk. Relative concentrations of lead, zinc and cadmium released depend on the leaching agent used. Cit ric acid leachates contain higher lead:cadmium and zinc:cadmium (but l ower lead:zinc) ratios than do acetic acid leachates from nominally id entical dishes. Repeated extractions with acetic acid show that even a fter 20 consecutive 24-h leachings many dishes still release lead in c oncentrations exceeding FDA limits. (C) 1997 Elsevier Science B.V.