By Luke Hall, PG
In June 2017, the Environmental Protection Agency released an update to the Regional Screening Levels. RSLs are referenced when interpreting analytical data collected from properties during environmental assessments to determine whether additional assessment is required. RSLs can be calculated for residential, commercial and industrial properties. They serve as a benchmark for site-specific concentrations of individual chemicals and potential contaminants in the soil, water and vapor.
Tioga regularly refers to the RSLs to evaluate laboratory analytical data from samples collected during Phase II ESAs, surficial soil screenings and other site assessments. Analytical results above the recommended RSL does not necessarily mean that a risk to human or ecological health is present at a property. However, it does indicate that contamination is present and the site needs to be more thoroughly assessed.
RSLs are calculated using individual constituents’ toxicity and their exposure and absorption factors. Research conducted by the Agency for Toxic Substances and Disease Registry, the EPA Integrated Risk Information System, the Provisional Peer Reviewed Toxicity Values for Superfund and other sources are all considered when updating RSLs.
The recent revisions to the RSLs include changes in the toxicity values of ammonia, petroleum hydrocarbon constituent trimethylbenzene, hydrogen sulfide, varieties of jet fuel and many more foreign chemicals. The revisions are a result of our deepened understanding of specific constituents and how they interact with the environment. The EPA is constantly improving RSLs to provide the most accurate measure for risk to human and ecological health from identified contamination.
Luke Hall is a professional geologist. He supervises and performs subsurface environmental assessments and remediation for a wide range of properties and sites.
Learn more about Tioga’s expertise in environmental assessments.