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TOXIC MODELING SYSTEM LONG-TERM (TOXLT)
Description:
The Toxic Modeling System Long-Term (TOXLT) is a personal-computer- based model that has been developed in conjunction with the release of the new version of the EPAs Industrial Source Complex (ISC2) Dispersion Models (EPA, 1992) and the promulgation of the EPAs A Tiered Modeling Approach for Assessing the Risks Due to Sources of Hazardous Air Pollutants (EPA-450/4-92-001). The purpose of TOXLT is to assist in the evaluation of the lifetime cancer risks and chronic noncancer hazards that may result from long-term exposure to toxic air pollutants. The ISCLT2 model is used to simulate annual average pollutant concentrations, which are then used to estimate cancer risk levels or hazard index values at each user-specified receptor. These outputs presume: 1) a hypothetical individual exists at each receptor; 2) no contribution from background sources (i.e., sources not specifically included in the simulation); and 3) pollutant contributions in a mixture are additive (i.e., there are no synergistic or antagonistic interactions between pollutants). Interpretation of TOXLT2 results should be mindful of the above mentioned assumptions and the inherent limitations of the ISC2 dispersion model.