Lead is a highly toxic metal that may cause a range of health problems, especially in young children. When lead is absorbed into the body, it can cause damage to the brain and other vital organs, like the kidneys, nerves, and blood. Lead may also cause behavioral problems, learning disabilities, seizures and in extreme cases, death. Some symptoms of lead poisoning may include headaches, stomachaches, nausea, tiredness,  and irritability. Children who are lead poisoned may show no symptoms.

https://www.hud.gov/program_offices/healthy_homes/healthyhomes/lead