The prevalence of elevated blood lead levels (BLLs) among U.S. children has declined sharply in the last decade primarily because of marked reductions of lead in residential paint, gasoline, and dietary sources. The prevalence of BLLs >10 μg/dL among children 1 to 5 years old declined from 9% to 1.6% between 1991 and 2002, but there remain communities and populations that bear a disproportionate burden of plumbism, with over 300,000 children remaining at risk for exposure to harmful levels of lead.

The ingestion of lead-containing dust is the primary source of lead exposure in children. The major sources of lead dust are disruption of lead-containing paint and soil. Other sources of lead exposure include water and contaminated clothing of adults who have occupational exposure to lead. Although lead-based paint has not been in use for decades in the United States, it is estimated that more than 20 million housing units still contain lead-based paint or lead-soldered pipes, units more likely to be in poor condition and occupied by low-income families. Risk factors for increased lead burden include:

Screening efforts focus on high-risk children from 1 to 5 years of age because they are most likely to ingest lead in their environment from increased hand-to-mouth activity. Furthermore, once ingested, lead is more easily absorbed in young children and their central nervous system is more vulnerable to its effects, as compared to adults. Neurotoxicity of lead includes acute encephalopathy as well as long-term impairment. Population-based studies consistently demonstrate impaired neurocognitive development in
children with a BLL >10 μg/dL even in the asymptomatic child. Further, a clear negative effect on cognition has been demonstrated with BLLs <10 μg/dL, previously thought to have little to no effect. Although intelligence is the primary outcome in most studies, there is evidence that lead is implicated in attention deficit and learning disorders as well.