This condition is generally true so long as the exposure assumptions match those accounted for in the calculations, and the site fulfills the conditions and assumptions of the generic conceptual model underlying the screening levels. Generally, at properties where subsurface concentrations of vapor-forming chemicals, such as those in groundwater or “near source” soil gas, fall below the recommended screening levels (i.e., VISLs), no further action or study is warranted. The primary objective of risk-based screening is to identify sites or buildings unlikely to pose a health concern through the soil gas intrusion pathway. A target hazard quotient of 0.1 for potential non-cancer effects.A target cancer risk level of one per million (10 -6) and.Default residential or nonresidential exposure scenarios.These screening-level concentrations (i.e., the VISLs) are based on: The calculator provides generally recommended, media-specific, risk-based screening-level concentrations for: The Vapor Intrusion Screening Level (VISL) calculator identifies chemicals that are considered to be sufficiently volatile and toxic to warrant an investigation of the soil gas intrusion pathway when they are present as subsurface contaminants.
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