Lead sulphide and traditional preparations: routes for ingestion, and solubility and reactions in gastric fluid.

Lead sulphide frequently occurs as a fallacious materia medica in traditional preparations used throughout the Moslem world. Although one of the least soluble lead compounds, use of this material as an eye powder has been directly associated with elevated blood-lead levels in children. Data are presented from animal studies which show the primary route for ingestion of the eye cosmetic is not transcorneal transport. Conversion of the sulphide to the more soluble (and hence more readily absorbed) chloride form is shown to occur in gastric fluid and, significantly, a marked dependence of the rate of dissolution on particle size is found. This may explain the disparity in previous reported values for the extent of absorption of ingested lead sulphide.