CDC updates blood lead reference value

Nov. 1, 2021

The Centers for Disease Control and Prevention (CDC) updated the blood lead reference value (BLRV) to 3.5 μg/dL from 5 μg/dL. The agency says the change “provides an opportunity for additional progress in addressing longstanding disparities in lead exposure and BLLs (blood lead levels) in children.”

The CDC said the BLRV should be used as a guide to determine whether medical or environmental follow-up actions should be initiated for a child with BLLs between 3.5 and 5 μg/dL who previously would not have been recommended to receive these services until their BLL reached 5 μg/dL.

In addition, the CDC says the test should be used to prioritize communities with the most need for primary prevention of exposure and evaluate the effectiveness of prevention efforts. Screening for BLLs should be done according to federal Medicaid and state requirements.

Scientific evidence suggests that there is no known safe blood lead level (BLL) because even small amounts of lead can be harmful to a child’s developing brain. In 2012, CDC introduced the population-based blood lead reference value (BLRV) to identify children exposed to more lead than most other children in the United States.

The BLRV is based on the 97.5th percentile of the blood lead distribution in U.S. children 1–5 years old from National Health and Nutrition Examination Survey (NHANES) data. NHANES is a complex, multistage survey designed to provide a nationally representative assessment of health and nutritional status of the noninstitutionalized civilian adult and child populations in the United States.

The initial BLRV of 5 μg/dL, established in 2012, was based on data from the 2007–2008 and 2009–2010 NHANES cycles.

The BLRV is a population-based measurement which indicates that 2.5% of U.S. children aged 1–5 years have BLLs ≥3.5 μg/dL. It is not a health-based standard or a toxicity threshold.

The most common sources of lead exposure in the United States are lead-based paint and dust, lead-contaminated soil, and lead in water from lead pipes and plumbing fixtures, the CDC said. Other sources of exposure include some toys and jewelry, candies imported from other countries, traditional home remedies, and certain jobs and hobbies that involve working with lead-based products and might cause parents to bring lead into the home.

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