How was toxicity of pollutants on the Air Toxics Priority List determined?
The Toxicity Subcommittee of the Air Toxics Advisory Committee used toxicity factors from the Environmental Protection Agency’s Risk-Screening Environmental Indicators (RSEI) model, and updated some of the factors based on updated toxicological information EPA published after the RSEI toxicity factors. The ATAC did not use the RSEI model itself to determine risk levels because the model was only designed as a screening tool to be applied to major industrial air toxic sources required to report to the Toxic Release Inventory (TRI). The RSEI model fails to incorporate other sources of air toxic risk posed to the public, including smaller industrial, commercial, residential, mobile, and biogenic (naturally occurring) sources.
