Lead migration from ceramicware in contact with foodstuff: effect of glaze, temperature, pH and food simulant

Lead (Pb) release from non-conforming flatwares and artisanal hollowwares was measured by ICP-AES. Influence ofacidic beverages (tomato juice, vinegar and lemon juice), food simulants (acetic acid, citric acid, and malic acid) at pH (2.37-5.00),contact time (t) (30 min-2 days), temperature (T) (20 °C-90 °C), and glaze were investigated. Pb release was lowest in tomato juiceand highest in lemon juice (t = 24 h; T = 22 °C). In acetic acid 4% (v/v) Pb release was 14% less than in lemon juice. Variabilitybetween the flatwares used for experiments in lemon juice and acetic acid 4% (v/v) corresponds to 3.48% and 7.03% respectively.According to the set of experiments where three food simulants were compared, it appeared that acetic acid, citric acid, and malicacid have the same leaching capacity above pH 3, but at pH < 3, citric acid appears to be the strongest extractant. Moreover, theinfluence of the applied ceramic glaze played an important role in lead release, in certain cases doubling the extracted amount of Pb.It has also been demonstrated that migration kinetics in citric acid is stronger. At 90 °C, after 2 h, the amount of extracted lead is18% more important than at 20 °C after 24 h in acetic acid 4% (v/v) which may question the capacity of consumer protection of ED84/500/EEC.