Answer :Beth Rosenberg, MPH, ScD, an assistant professor in Tufts Department of Public Health and Community Medicine, replies: Lead is definitely harmful for adults to ingest or breathe, a fact known since the second century AD, when a Greek physician named Dioscorides said, Lead makes the mind give way. Of course, the greater the exposure, the more severe the symptoms.
Many people wonder about lead in ceramic products. Lead traditionally has been used in paints and glazes for good reason: It makes the coating more durable. According to experts in the field, lead can be in the ceramic itself, the paint applied to the item or the glaze that coats the outer surface. There is no way to tell about the presence of lead other than testing. The country of origin apparently makes no difference; one lead tester found lead-as well as arsenic, cadmium and mercury- in ceramics from the US, China, Mexico, Australia and Iran.
Heat and acid facilitate the leaching of lead into food and beverages, so its advisable not to let acidic beverages like coffee sit for hours in ceramic mugs, especially if the glaze is chipped or scratched. Unless its clearly stated that the ceramic is lead free, consider buying your coffee mug from your local knowledgable potter-those ceramics are the least likely to contain lead.