In 1971, the U.S. Centers for Disease Control and Prevention (CDC) investigated lead exposure in El Paso, Texas, and discovered its effects on children’s brain and neural development.

The Lead-Based Paint Poisoning Prevention Act of 1971 required the Secretary of Health, Education, and Welfare (now Health and Human Services) to define paint chips as the primary health hazard of lead-based paint and to set the level of lead in blood warranting “concern” at 60 μg/dL (Public Law No. 91-965; January 13, 1971).

Subsequently, a U.S. Surgeon General’s report defined a blood lead concentration of 40 ﾵg/dL to be considered evidence suggestive of ‘undue absorption of lead, either past or present,’ and defined ‘lead poisoning,’ as confirmed, on 2 successive determinations, BLLs of 80 ﾵg/dL or more with or without symptoms.

Later that year, the US Surgeon General’s report on “Medical Aspects of Childhood Lead Poisoning” emphasized the need to shift the focus from identifying children with overt poisoning to prevention through early detection of children with “undue absorption of lead.”

The CDC became involved in defining the criteria for interpreting BLLs in children issuing its first statement on ﾓIncreased Lead Absorption and Lead Poisoning in Young Children.