What blood lead level is considered normal for children, adults (including pregnant women), and in occupational screening?

Normal Blood Lead Levels

There is no safe or "normal" blood lead level—any detectable lead is harmful, particularly to children's neurodevelopment. 1, 2

Current Reference Values by Population

Children

• The CDC historically used 10 µg/dL as an action threshold, but this does not represent a safe level. 1, 2 Evidence demonstrates neurodevelopmental harm occurs below 10 µg/dL. 1, 2
• Current population data (2013-2014) shows the 97.5th percentile for children aged 1-5 years is 3.48 µg/dL. 3 This represents the upper range of contemporary exposure, not a safety threshold.
• Blood lead levels ≥5 µg/dL now affect only 0.5% of U.S. children (2013-2014), down from 9.9% in 1999-2000. 3

Adults (Non-Occupational)

• Mean blood lead levels in the general U.S. adult population have declined to 0.84 µg/dL (2013-2014). 3
• The geometric mean for adults aged 20-59 years in NHANES III was 2.51 µg/dL. 1
• Health effects including hypertension, renal dysfunction, and cognitive impairment can occur at concentrations <40 µg/dL. 4

Pregnant Women

• Pregnant women should avoid any lead exposure resulting in blood lead levels >5 µg/dL. 4 Lead mobilizes from maternal bone during pregnancy, creating internal fetal exposure. 5
• Removal from occupational lead exposure is mandatory during pregnancy. 4

Occupational Screening

• OSHA requires blood lead monitoring for workers exposed to airborne lead ≥30 µg/m³, though testing should be considered for all lead-exposed workers. 6
• Action levels for occupational exposure:
  • 10-19 µg/dL: Quarterly monitoring required 4
  • ≥20 µg/dL (two successive measurements over 4 weeks): Removal from exposure 4
  • ≥30 µg/dL (single measurement): Immediate removal from exposure 4

Critical Clinical Context

Why "Normal" Is Misleading

• No safe threshold has been established—lead affects neurocognitive function, behavior, and physical development at levels previously considered acceptable. 1, 2
• Research since 1991 demonstrates children's physical and mental development is impaired at blood lead levels <10 µg/dL. 2
• In children, effects have been convincingly demonstrated at 10-15 µg/dL, with no identified no-effect level. 7

Laboratory Considerations

• Federal regulations permit laboratory error of ±4 µg/dL or ±10% (whichever is greater), meaning a true value of 7 µg/dL could be reported anywhere from 3-11 µg/dL. 1
• Select laboratories achieving routine performance within ±2 µg/dL rather than the federally permitted ±4 µg/dL. 6, 2
• Venous blood is the gold standard—capillary samples are prone to skin contamination and should only be used for initial screening, with any elevated result confirmed by venipuncture. 6

Common Pitfalls

• Assuming blood lead <10 µg/dL is "safe" or requires no action—this outdated threshold does not protect against neurodevelopmental harm. 1, 2
• Using capillary samples for diagnostic purposes rather than confirmation with venous blood. 6
• Failing to recognize that population reference ranges reflect current exposure patterns, not biological safety thresholds. 3