Although lead-based paint has been banned in the US since 1978, any home built before that time could—and should be assumed to—be a potential source of lead poisoning.
You may not see any peeling paint, but lead dust enters the air when painted surfaces rub against each other, like when you open doors or windows. Lead also becomes a danger during renovations, when old paint may be scraped or sanded.
There are very strict rules about construction and renovation when lead is present, but not all contractors are following them or checking the dates on homes before they begin work. If your house was built before 1978, have it tested for lead and if you are going to do any renovations, have a certified lead removal contractor take care of all lead-based paint before you do the work.
Lead is extremely dangerous and even a very tiny amount can cause permanent brain damage in children. Here is a video from a news station in Portland, Oregon about a family who thought they were safe, but fell victim to an irresponsible renovator with dire consequences to their 3 children.