In many homes built prior to 1978, lead is a common problem. It could be that the pipes in your home are made from lead, or it could be paint on the walls that has lead added to it.
It is fairly easy to detect lead in your home. Lead paint will flake in a way that looks like scales from a snake, and pipes made from lead will scratch easily when scraped with a sharp, hard object.
If you do suspect that there might be lead in your home, you should take steps to have it removed. Exposure to lead is dangerous for humans and can lead to birth defects. It is extra dangerous for young children since their bodies can absorb it faster.
Very young children could be exposed from eating paint chips, so you should make sure that they are kept away from any areas where the paint is chipping.