Characterization of lead and lead leaching properties of lead glazed ceramics from the Solis Valley, Mexico, using inductively coupled plasma-mass spectrometry (ICP-MS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT)

Abstract

Ingestion of relatively small amounts of lead is now recognized to cause significant neurological and cognitive effects in humans. Large quantities may be fatal, yet lead poisoning, especially of children, is still a major public health concern in many parts of the world. In rural Mexican communities lead oxide (PbO) is added to ceramic glaze as a fluxing agent, lowering starting firing temperatures to 500 °C. The purpose of this study is to characterize the lead chemical forms in ceramic glazes from the Solis Valley, Mexico, to investigate lead leaching properties of these ceramics, and to demonstrate the applicability of lead isotope signatures as a means of tracing lead source origins. Ceramics were collected from the rural village of Santa Maria de Canchesda, State of Mexico, Mexico. Dried liquid glazes, post-fired glaze material, and pure PbO were analyzed by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). Results from DRIFT analysis indicate that PbO (1429 cm −1 band) is the active form of lead found in liquid glazes and ceramics. Some shifting of 1429 cm −1 PbO peak to lower wavenumbers occurs in post-fired ceramics, and this may be due to the formation of lead bisilicate during firing. Ceramics samples were leached in 0.02 M citric acid solution for 1 min, and leached lead concentrations were measured using inductively coupled plasma-mass spectrometry (ICP-MS). Lead concentrations in these leachates varied from 0.4–80.4 μg ml −1, while the control pottery from the US leached only 0.1 μg ml −1 lead. Elemental distributions on glaze surfaces were identified by laser ablation (LA)-ICP-MS. Nitric acid extracts of soils, teeth, and ceramic glazes were analyzed for lead isotope ratios ( 207Pb/ 206Pb vs. 208Pb/ 206Pb) using ICP-MS. Similarities of tooth and ceramic lead isotope ratios indicate that ceramics may be a substantial source of body lead burden in the Solis Valley. This study demonstrates the applicability of lead isotope ratios for lead source identification, and it identifies potential health risks from ceramic use induced lead toxicity within the Solis Valley.