Development of a Stochastic Blood Lead Prediction Model.* Robert C. Lee, William E. Wright, and Walt Haerer, Golder Associates, 4104 148th Ave. NE, Redmond, Washington 98052; and James R. Fricke, Asarco Inc., 3422 South 700 West, Salt Lake City, Utah 84119
A partially stochastic blood lead prediction model has been developed, based on the U.S. Environmental Protection Agency Integrated Exposure/Uptake/Biokinetic blood lead model (LEAD model). The LEAD model is deterministic, and does not propagate uncertainty in exposure variables. In the present effort, the LEAD model has been translated into a spreadsheet format. The uptake submodel incorporates probability distributions for exposure and bioavailability parameters. These distributions are developed using site-specific data and information from the literature. The biokinetic submodel is duplicated with a table incorporating partitioning and decay of lead levels in the body. Uptake parameter uncertainty is propagated in the model by the use of Monte Carlo simulation. Thus, sensitivity analysis is possible, and driving variables can be determined. Application of the model to a lead-contaminated site is demonstrated. The stochastic model produces more realistic estimates of lead uptake than the deterministic model. Driving variables include bioavailability of lead and dietary intake of lead.
*Work funded by Asarco Corporation.