March 15, 2024
US EPA lowered the guidance levels for lead in residential soil at CERCLA sites and RCRA Corrective Action facilities from 400 parts per million (ppm) to 200 ppm, or 100 ppm in areas with multiple sources of lead exposure.
On January 17, 2024, the US Environmental Protection Agency (US EPA) lowered the regional screening level (RSL) and regional removal management level (RML) for lead-contaminated soil in residential areas from 400 ppm to 200 ppm. Furthermore, US EPA proposed an RSL of 100 ppm in residential areas with additional sources of lead exposure, including lead water service lines, lead-based paint, and non-attainment areas where air lead concentrations exceed National Ambient Air Quality Standards (NAAQS). This updated guidance applies to Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) sites (more commonly known as “Superfund” sites) and Resource Conservation and Recovery Act (RCRA) Corrective Action facilities.
The previous RSL of 400 ppm in residential areas, which was in effect for more than three decades, was based on a target blood lead level (BLL) of 10 μg/dL in children. To derive the revised lead soil guidance levels of 200 and 100 ppm, US EPA used a target BLL of 5 μg/dL and 3.5 μg/dL in children, respectively. A BLL of 5 μg/dL was the Centers for Disease Control and Prevention (CDC) blood lead reference value (BLRV) until 2021, at which time the BLRV was updated to 3.5 μg/dL. The current BLRV of 3.5 μg/dL means that the CDC estimates that 97.5% of US children aged 1 to 5 years have BLLs at or below 3.5 μg/dL. The CDC has stated that the BLRV is neither a health-based toxicity value nor a regulatory standard.
The updated soil lead guidance applies to all residential sites subject to CERCLA response and RCRA Corrective Action authorities, including sites previously addressed and/or deleted from the National Priorities List. Because a substantial number of properties are expected to undergo evaluation due to this updated guidance, US EPA does not expect all regions to be able to address all properties immediately. US EPA regions will continue to use the existing prioritization process to determine what sites will be evaluated and remediated.
US EPA noted that screening levels are not cleanup standards, and the impact of lower screening levels will depend on how this guidance is applied in specific states. Indeed, US EPA states in its guidance, “While this update will help EPA site teams make site-specific cleanup decisions to protect nearby communities, EPA makes cleanup decisions specific to each site, using site-specific factors, including risk factors and community input that can vary from site to site.” US EPA cautioned, however, that cleanup levels for lead-contaminated sites should not be set at values below natural background levels of lead in soil. According to US EPA, urban background soil lead concentrations can be as high as 2,500 ppm but vary greatly across cities.
For more information, refer to US EPA’s website and/or contact Gradient.
Steven R. Boomhower, Ph.D.
Senior Toxicologist
Kyle J. Colonna, Ph.D., M.P.H.
Epidemiologist
Rosemary L. Mattuck, M.S.
Senior Environmental Engineer