The lead paint picture isn't pretty. Toxic levels can lead to all sorts of intellectual and neurological disabilities, developmental delays, behavioral problems, kidney disease, anemia, and — not to scare freak you out too bad but, worst case scenario — death. Even "low levels" may be associated with learning issues and decreased IQ.
Thanks to their tendency to put oh... anything in their mouths, kids under three are at greatest risk. Lead paint chips often have a sweet taste, making it especially dangerous — check out these tips for keeping your home safe. Also, only let baby teethe on age appropriate toys, and never let him put anything with peeling paint in his mouth.
If you think baby might have been exposed to lead, ask your pediatrician to check his lead levels. All children also receive these tests routinely, so baby may actually have already been checked out.