Hot Leaching of Ceramic and Enameled Cookware: Collaborative Study

Abstract

A hot leach method published by the World Health Organization for determining Pb and Cd in ceramic and enameled ware was collaboratively studied in 14 laboratories. The method consisted of heating a solution of 4% acetic acid at the boil for 2 h in 6 samples of specially glazed ceramic ware and 6 samples of special enameled ware. The acid was allowed to cool and stand in contact with the ware for an additional 22 h. At the end of the 2 h heating period and again at the end of the 24 h period, the leach solution was assayed by atomic absorption spectrophotometry for Pb and Cd. Ruggedness testing before the collaborative study revealed that: (1) the quantity of metal released increased as the average leach temperature approached the boiling point, (2) the quantity of Pb and Cd released from enameled ware increased linearly with time during 7 h of boiling, (3) the concentration of acid could be varied from 2 to 6% with no apparent effect on the amount of metal released, and (4) the room temperature (RT) contact period lasting from 22 to 120 h (after the 2 h heating period) did not increase the amount of metal released. The quantities of Pb and Cd measured by the collaborators at the end of 2 h of heating and after 24 h of total contact were essentially identical. The amounts of Pb and Cd were not related to the quantity of acid solution required to restore the leach solution volume to its initial value after boiling. The collaborative results showed that the period of standing at RT is not necessary and probably can be eliminated from the method. The modified method, which requires analysis of the leach solution immediately after the 2 h heating period, has been adopted interim official first action by AOAC.

Lead Migration from Ceramicware in Contact with Foodstuff: Effect of Glaze, Temperature, pH and Food Simulant

“…For each pH, before attending the plateau, a linear relationship between the contact time and the amount of released Pb was found. The same relationship was found by Gould et al [26]. For each pH, the slope of the fitted linear model was calculated.…”

Migration of Iron and Aluminum From Different Cookwares to Faba Bean After Cooking Cycles and Storage Refrigerated

“…(Tassi et al, 2014) studied the migration of Cu, Cr, Cd, Al, Fe, Mn, Ni, and Pb from carbon steel cylinders to food gases and stored up to 50 day, the migration was lower for metals. (Quintaes et al, 2006) (Gould et al, 1983). Raw faba bean mean : faba bean before cooking.…”

Lead, Cadmium and Cobalt (Pb, Cd, and Co) Leaching of Glass-Clay Containers by pH Effect of Food

“…The leaching of metals induced by acetic acid, which was used to simulate the prolonged use of the containers, shows that metal leaching increases with increased use of the containers. This method to establish the amount of metals that are leached by acetic acid has been well utilized by several authors [ 37 , 41 – 44 ], who have shown that clay containers from Mexico, Italy, and other countries have high concentrations of heavy metals, mainly lead, surpassing the limits allowed by the FDA.…”

“…Despite the fact that the lowest levels of leached cadmium and lead were found in Tulancingo, these levels remain higher than those reported by Gould et al ., in 1983 [ 41 ]. However, there are works in which even greater leaching of both metals have been reported [ 37 , 42 – 44 ].…”

“…The results found during the clay vessel re-usage experiments for the leaching of Pb and Cd show that the concentration of heavy metals leached by the clay containers in this study is greater than those reported by Gould et al . in 1983 [ 41 ] and by González de Mejía et al in 1996 [ 37 ]. Several authors ascribe greater importance to metals such as Pb and Cd because these are mainly found in glass-clay containers [ 37 , 42 – 44 ], affording little importance to metals such as Co because its effects are not as severe as those reported for Cd and Pb.…”