Integrated Stochastic Exposure (ISE) Model

Software last updated May 21, 2003. Click on the button to download the ISE Model Software.

The Integrated Stochastic Exposure (ISE) Model is a probabilistic exposure model developed by SRC for use in childhood lead risk assessments. ISE uses the same exposure, uptake, and biokinetic variables as the U.S. EPA IEUBK Model for Lead in Children.

Users can input a wide range of probability distributions for exposure and uptake variables, and run Monte Carlo simulations to quantify variability (1-dimensional Monte Carlo analysis) or both variability and uncertainty (2-dimensional Monte Carlo analysis). ISE will yield the same geometric mean blood lead concentrations (PbB) as the IEUBK model when the same set of point estimates are used for input variables. ISE generates summary statistics of the probability distribution for PbB at 1-year age groups (ages 0 to 6 years). Toggles are available to generate text files with inputs (exposure values) and outputs (pathway-specific uptakes and PbBs), which can be easily imported to other statisical software for data analysis and graphing.

Novel features include: a simulation option to specify alternative time steps for exposure (daily, monthly, quarterly, and annual); serial autocorrelation approach to quantify interindividual variability in soil ingestion rate for consecutive time steps (random, or fixed decile); and the ability to save input selections, including a seed for the random number generator. A user's guide is included with documentation of the random number generator, algorithms for specifying probability density functions, and alternative parameter input options such as arithmetic and geometric parameters, and truncation limits.

While ISE v.1.4.1 is freeware, it is currently a research tool and SRC would appreciate any feedback or notification of runtime bugs.