What is a normal lead level in blood?

Normal Blood Lead Levels

There is no safe blood lead level, as even low levels of lead exposure can cause adverse health effects, particularly in children. 1, 2

Current Reference Values and Trends

The CDC and World Health Organization have historically used the following reference values:

• In 1991, a blood lead level of 10 μg/dL was established as the threshold of concern 1, 3
• More recent evidence shows harmful effects at levels below 10 μg/dL 2, 3
• During 1999-2002, the geometric mean blood lead level for U.S. women aged 20-59 years was 1.2 μg/dL 1

Population-Specific Considerations

Children

• Blood lead levels in children have decreased substantially since 1976 1
• Children's blood lead levels typically follow a pattern:
  • Newborn infants' levels reflect maternal levels 1
  • Levels increase beginning in late infancy
  • Peak levels occur at 18-36 months of age 1
  • Studies show cognitive impairment at levels below 10 μg/dL 4

Adults

• Research shows increased mortality risk at blood lead levels as low as 3.6 μg/dL compared to levels below 1.9 μg/dL 3
• A 25% excess risk for all-cause mortality and 55% for cardiovascular mortality has been observed at these levels 3

Laboratory Considerations

When interpreting blood lead test results, be aware of important limitations:

• Federal regulations allow laboratories to operate with a total allowable error of ±4 μg/dL or ±10%, whichever is greater 1
• At levels below 10 μg/dL, this means significant variability in results
• Example: A true value of 7 μg/dL could be reported anywhere from 3-11 μg/dL 1
• Collection method matters:
  • Capillary samples (fingerstick) may be contaminated by lead on skin
  • Elevated capillary results should be confirmed with venous samples 1

Clinical Implications

• Environmental assessment is recommended for children with blood lead levels ≥5 μg/dL 1
• Neurological symptoms can occur at various levels:
  • Irritability, headaches, concentration difficulties at low levels 2
  • Neurobehavioral symptoms in children at 10-35 μg/dL 2
  • Acute encephalopathy at >80-100 μg/dL in children and >100 μg/dL in adults 2

Prevention Priorities

• Identify and eliminate lead sources in older housing (pre-1960) 1
• Test water sources, particularly in older buildings and schools 1
• Screen high-risk populations, including immigrant and refugee children 1
• Recognize that prevention is the most important approach, as there is no safe threshold 2

Blood lead testing should be interpreted with caution due to laboratory variability, and any detectable lead should prompt consideration of potential sources of exposure, particularly in children and pregnant women.