Prof John Little
Virginia Tech (VT)
Department of Civil and Environmental Engineering
401 Durham Hall
Tel. (540) 231 0836
Christiaan Delmaar, National Institute for Public Health and the Environment (RIVM), Bilthoven, NL, email@example.com
Human exposure to semi-volatile organic compounds (SVOCs) present in materials is of great interest because of the large number of SVOCs used for different purposes in different materials; ranging from plasticizers in PVC to flame retardants in upholstery and clothing to solvents in paints or pesticides in wood finishes. Very recent findings brought important advances in estimating critical emission parameters necessary for exposure assessment of chemicals in many materials. The inclusion of this new knowledge in existing exposure assessment tools such as DustEx is crucial for their reliability and applicability.
In indoor environments, it has been shown that exposure can occur via inhalation of air and airborne particles, direct dermal contact, dermal uptake via air, and incidental ingestion of contaminated dust. Dust is particularly interesting because it is not only a potential exposure pathway, but also accelerates SVOC emissions by serving as a sink and thus allowing additional SVOCs to be emitted from a material.
The DustEx tool, which was developed as part of the LRI project B12-ETHZ, takes these considerations into account and simulates potential exposures based on a range of input parameters. To further improve and build confidence in the tool, we propose the following research objectives, building on our recent findings:
1) Integration of a newly established, theoretically-based relationship between C0 (the material-phase concentration of an SVOC in a material) and y0 (the equilibrium concentration in the gas phase in contact with the material surface) for phthalates and phthalate alternatives in PVC products in the DustEx tool.
2) Inclusion of our knowledge of the surface/air partition coefficient KS in the DustEx tool, especially of its dependence on the roughness of the surface.
3) Conceptual validation of the DustEx tool for simple indoor conditions by conducting chamber experiments and solving the mass balance using the updated DustEx tool, thus giving confidence to the overall modeling approach. Previous validation efforts in real-world environments were insufficient because of the high level of complexity in these environments.