Crews have been working after school hours to clean art rooms at 15 Milford schools that tested positive for lead. The Milford Health Department issued a warning to parents about possible lead poisoning after lead glazes were found in school art studios. The health department says poisoning is possible from continued inhalation of fumes while the pottery bakes, or if someone repeatedly eats or drinks from pottery with lead in it. All kilns in the schools have been shut down and environmental cleanup crews have been called in. Lead glazes have been banned from schools for at least a decade. A spokesman for the Milford School District says they have not determined whether the glazes were never removed or whether they were donated in recent years. Officials from the Milford Board of Education say clean up should last for the next several weeks and may cost as much as $50,000.