Stochastic Human Exposure and Dose Simulation (SHEDS)
SHEDS-Multimedia version 3 is a probabilistic aggregate residential exposure model. Other SHEDS models, with similar approaches but addressing different chemical classes and exposure scenarios, have been developed by EPA/ORD’s exposure modeling research program to address exposures to particulate matter (SHEDS-PM), air toxics (SHEDS-ATOX), and wood (SHEDS-Wood) This modeling tool can help predict ranges of exposure in a population, enhance dose model estimates, identify critical pathways and factors, quantify uncertainties, and compare model predictions against real-world data. It has a number of unique features that advance the science of human exposure assessment, and has been peer reviewed and applied for research and regulatory support. SHEDS can link with measurements, source models, and PBPK models to quantify and reduce uncertainty in risk assessments.
Residential-SHEDS is a physically based probabilistic model which simulates dermal and nondietary ingestion exposure of individuals to pesticides from residue on various surfaces in the home and from turf in the residential yard. It generates daily exposure and dose time profiles using mechanistic equations. Exposure is modeled as a series of transfers, using a microactivity approach. EPA's SHEDS-Residential version 4 model is a physically-based, probabilistic model that can simulate for a population of interest cumulative (multiple chemicals) or aggregate (single chemical) residential exposures over time via multiple routes of exposure for different types of chemicals and scenarios. The United States Environmental Protection Agency, through its Office of Research and Development, developed and funded SHEDS-Residential version 4 with assistance from contractor Alion Science and Technology, Inc.
SHEDS-Residential version 4 is one module (along with the separate SHEDS-Dietary module) of EPA’s more comprehensive human exposure model, the Stochastic Human Exposure and Dose Simulation model for multimedia, multipathway chemicals (SHEDS-Multimedia), which can simulate aggregate or cumulative exposures over time via multiple routes of exposure (dietary & non-dietary) for different types of chemicals and scenarios. SHEDS-Residential and SHEDS-Dietary will be merged together in a future version of SHEDS-Multimedia.
SHEDS-Residential version 4 includes a case study example for illustrative purposes, as well as a default file for non-chemical specific inputs, as described in the Technical Manual and User Guide. All input values used in the SHEDS-Residential model for a given application should be entered or reviewed by the researcher so that the model results are based on appropriate data sources for the given application.