LEAD POISONING: Lead is a heavy metal that has very negative effects on the brain. It is particularly dangerous for young children because a developing brain is more sensitive to lead exposure than a fully developed brain. Years ago lead was the leading cause of mental retardation. But since the 70’s, lead-based paint was no longer used in homes and the number of kids with lead exposure decreased. In the 90’s, doctors stopped doing universal checks for lead in the blood, since the exposure was not as common. A blood test can determine if a child has lead in their body, however, sometimes if the lead has been in the body for awhile, the lead can move into the bones and tissue and will not show up on a blood test.