In 2012, the US Centers for Disease Control and Prevention (CDC) adopted a blood lead reference value of 5 micrograms per deciliter and recognized that there is no known health-based threshold for effects in children. Previously, the agency had identified a “level of concern” implying that blood lead levels (BLLs) under 10 micrograms per deciliter were not associated with harm. In making the switch, there was purposeful intent to recognize that there is no safe level of lead exposure and therefore a new classification system was needed to identify and prioritize the most highly exposed.1 The reference value is an action level at which the CDC recommends environmental investigations to identify sources of lead exposure in a child’s home.
