EPA's RSL/RML description

The US Environmental Protection Agency Regional Screening Levels (RSLs) are chemical-specific concentrations for individual contaminants in air, drinking water and soil that, if exceeded, may warrant further investigation or site cleanup. The Regional Removal Management Levels (RMLs) are chemical-specific concentrations for individual contaminants in tap water and soil that may be used to support the decision for EPA to undertake a removal action. The RSLs and RMLs are risk-based levels, calculated using the latest toxicity values, default exposure assumptions and physical and chemical properties. They are updated twice a year. For more information, please see the RSL (https://www.epa.gov/risk/regional-screening-levels-rsls) and RML (https://www.epa.gov/risk/regional-removal-management-levels-chemicals-rmls) websites.