Lead is a heavy metal in the earth that can be harmful to humans.

Lead exposure can occur by ingesting water, food, objects, or soil that is contaminated by lead or by breathing air that contains lead dust. Common sources of lead include chipped or peeling paint in older houses, water from lead pipes, and soil near highways, factories, or airports. Certain jobs (such as construction, battery manufacturing, and mining) and hobbies (such as repairing old homes or using pigments that contain lead) are linked to lead exposure. Some imported toys, jewelry, traditional medicines, spices, and candies may also contain lead.

Lead poisoning usually causes no immediate symptoms, but over time, lead causes damage to developing brains, so children exposed to lead (even at low levels) can have slowed growth and development and problems with learning, behavior, hearing, and speech that may be permanent. Adults with lead poisoning are at increased risk of high blood pressure, heart disease, decline in cognitive function, anxiety, depression, and death.

Young children are at highest risk of lead poisoning because they are most likely to put their hands or objects containing lead into their mouths. Children who are immigrants, refugees, or recently adopted from resource-limited countries are at increased risk if there is less strict regulation of lead exposure in their country of origin. During pregnancy, lead can be passed through the bloodstream to a fetus. Lead can also be transmitted through breastfeeding.

Lead poisoning is diagnosed with a blood test, which should be done for individuals considered at risk of lead exposure. Although a safe lead level has not been identified, the Centers for Disease Control and Prevention (CDC) defines elevated blood lead in children as 3.5 micrograms per deciliter (μg/dL) or higher. For adults, a blood lead level greater than 5 μg/dL is defined as elevated based on the National Institute for Occupational Safety and Health/CDC Adult Blood Lead Epidemiology and Surveillance Program.

Treatment of lead poisoning includes identifying and removing the source of lead, a diet high in calcium and iron, and careful monitoring of blood lead levels. Individuals with a very high blood lead level may receive specialized treatment (chelation therapy) to remove lead from their bodies.

Lead poisoning can be prevented by removing or decreasing exposure to lead. Homes in the US built before 1978 often have lead paint, which can be detected by a licensed lead inspector, and should be removed by contractors certified by the Environmental Protection Agency. Homes with lead pipes should be fit with specialized water filters to decrease lead levels, and only bottled water or cold water should be used for drinking and cooking because hot water has higher lead levels. Prior to making a purchase, check the US Consumer Product Safety commission website for products that have been recalled due to high lead levels (www.cpsc.gov/recalls). To decrease the risk of spreading lead-contaminated dust in a home, shoes should be removed when entering. Individuals who work with lead should change their clothes before coming home, keep their shoes and tools outside, and wash their clothing separately from those of other household members.