This report describes the process and results of a project to improve the Health Risk Assessment (HRA) computer program. The major scientific objectives of this project were to evaluate the existing program in order to identify changes that can increase the capability, efficiency, and flexibility of the program: to modify the program so as to incorporate these changes; and to modify the algorithms and intermedia transfer factors as directed by the Office of Environmental Health Hazard Assessment (OEHHA) and the Air Resources Board. Several modifications were implemented to make HRA 2.0 faster and more efficient than HRA 1.1. As a result, calculation algorithms are now more efficient, the calculation time has been reduced and some temporary files have been eliminated. There are a number of changes in HRA 2.0 that make the program more users friendly and flexible relative to HRA 1.1. Creating, editing, and viewing the input files has been improved. Viewing reports on screen has also been improved. All changes to the HRA program were made in consultation with ARB and OEHHA staff. A summary comparison of HRA to the CAirTOX model is provided as extra information. This comparison for the arsenic and TCDD releases to air reveals that there are a number of similarities and some significant differences in the exposures predicted by these two multipathway models.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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