The authors point out that even low levels of lead exposure can affect a child’s psychomotor development. Young children are particularly at risk because they ingest lead more frequently due to their hand-to-mouth behavior, because their rate of intestinal absorption is high, and because their nervous system is still developing. The primary source of poisoning is old, deteriorated paint. Industrial lead, lead drinking water pipes, and certain more specific sources may also be implicated. The authors then describe the establishment of the National Surveillance System for Childhood Lead Poisoning (SNSSI) in 1995 and its evolution following the introduction of mandatory reporting. More specifically, the authors outline the information-gathering process involving: the prescribing physician, the testing laboratory, the poison control center, the DDASS, and the InVS.