If you are asking yourself, ‘What is lead poisoning?’ chances are that you fear you or someone you know has been exposed to lead. Lead, inhaled or otherwise ingested, can be harmful in large amounts or over an extended period of time. Lead poisoning can cause brain defects, cancer, and more. Lead is most commonly found in the paint throughout older homes. If you fear that you or someone you know has been exposed to lead, contact your local health department.