US CDC Adopts Lower Blood Lead Reference Value
On October 29, 2021, the US CDC adopted an updated blood lead reference value (BLRV) of 3.5 μg/dL—a reduction from the previous BLRV of 5 μg/dL established in 2012.
The BLRV is a population-based measurement and has decreased to reflect continued decreases in blood lead concentrations in US children across time.
The updated BLRV is based on the 97.5th percentile of the blood lead level distribution in US children aged 1-5 years as measured in the 2015-2016 and 2017-2018 cycles of the National Health and Nutrition Examination Survey (NHANES). The BLRV is not a health-based value or toxicity threshold; rather, it is a measure of a specific distribution of BLLs in a specific population at a specific time (CDC, 2021).
The updated BLRV could have significant implications for projects involving human health exposure, site remediation, or human health risk assessment. For example, because CDC calls for the BLRV to be updated every 4 years based on the most recent two NHANES cycles, this could mean that cleanup levels for lead-contaminated sites undergoing remediation could potentially have to be developed every four years. It would also be challenging to use the updated BLRV for most site remediation situations because cleanup levels may be less than urban background.