Enhanced Leaching of Soluble Lead by Cooking Acidic Food in Glazed Pottery Sold at the Mexico-US Border

The use of traditional glazed-clay pottery is associated with elevated blood lead levels and is one of the main factors of nonoccupational lead exposure in the Mexican population. Most of the traditional Mexican foods are acidic. Lead leaching from pottery into acidic foods increases the potential for lead exposure in individuals consuming food cooked in these items.

To explore the possibility that cooking traditional Mexican acidic dishes in lead-glazed pottery cookware enhances lead leaching compared to nonacidic dishes.

A sample of 33 glazed-clay pottery items sold in Reynosa City, Tamaulipas, Mexico, was collected. The official Mexican regulatory test for lead leaching was conducted using 8 cookware items. Twenty-five lead-glazed ceramic items were used to evaluate the soluble lead by testing the leaching ability of acidic (13 cookware items) and nonacidic (12 cookware items) traditional Mexican dishes. Similarly, acidic and nonacidic foods were cooked in standard cookware for comparison. The lead content in food was determined by atomic absorption spectrophotometry after acid digestion.

Only 1 of the cookware items met the lead leaching standards established by the Mexican regulatory guidelines, whereas the other 7 exceeded the maximum permissible level of leached lead. Acidic food cooked on glazed pottery showed a median lead concentration of 103.4 mg/kg (IQR = 14.8-186.1), whereas nonacidic food cooked on glazed pottery showed a median lead concentration of 11.19 mg/kg (IQR = 2.17-27.82 mg/kg; P < .05), indicating that acidic food extracted 9 times lead compared to nonacidic food when cooked in traditional ceramics.

Cooking acidic dishes with earthen pottery cookware resulted in significantly higher lead leaching than cooking nonacidic foods. The consumption of a single portion of acidic food prepared in lead-glazed ceramics produces a significant increase in blood lead levels and resulting health consequences.