Indoor Chemical Exposure Classification/Ranking Model (ICECRM)

The Indoor Chemical Exposure Classification/Ranking Model (ICECRM) is a steady-state model for the screening-level assessment of near-field human exposure to neutral organic chemicals released indoors. ICECRM adopts an existing multimedia indoor chemical fate model and couples it with exposure routes to humans and a human toxicokinetic model. Modifications of the indoor chemical fate model include (1) a particle mass balance, (2) consideration of the orientation of indoor surfaces; and (3) allowing for the possibility of human feedback on the chemical mass balance in the indoor environment. The human model includes three compartments (hand skin surface, rest of body skin surface, rest of the human body). The first two compartments are separated from the main body because chemicals on hands and skin surfaces contribute to human exposure indoors via hand-to-mouth transfer and dermal permeation, respectively. By considering human feedback on the overall indoor mass balance, the model probes how human intake and elimination (biotransformation, renal clearance) impacts its overall fate indoors.

The ICECRM model considers the following “indirect” chemical exposure pathways to humans: 1) inhalation of gaseous and particulate chemicals in indoor air, 2) non-dietary ingestion of dust and through hand-to-mouth contact following indoor surface contact, and 3) dermal permeation. The model equations, formulated in fugacity notation and programmed in Visual Basic for Application (VBA) in Excel™, quantify chemical transport, degradation, distribution and exposure processes for up to 10,000 chemicals at a time. Full details of the model are available in the following publication:

– Zhang, X.M.; Arnot, J.A.; Wania, F. 2014. A model for screening-level assessment of near-field human exposure to neutral organic chemicals released indoors. Environ. Sci. Technol. 48 (20), pp 12312–12319 DOI: 10.1021/es502718k

The ICECRM model is implemented (coded) in Visual Basic for Applications (VBA) and the Graphical User Interface is designed in Excel™. A User Manual is embedded within the Excel file. The ICECRM model will only function properly on a Windows operating system. The computer must use the period (.) as the decimal separator rather than the comma (,) to ensure accurate results.