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High Throughput Exposure Modeling of Semi-Volatile Chemicals in Articles of Commerce (SOT)
Citation:
Nicolas, C., M. Goldsmith, R. Pearce, Woodrow Setzer, AND J. Wambaugh. High Throughput Exposure Modeling of Semi-Volatile Chemicals in Articles of Commerce (SOT). Presented at SOT 2015, San Diego, CA, March 22 - 26, 2015. https://doi.org/10.23645/epacomptox.5178892
Impact/Purpose:
poster presented at SOT annual meeting in San Diego, CA on March 23, 2015.
Description:
Chemical components of consumer products and articles of commerce such as carpet and clothing are key drivers of exposure in the near-field environment. These chemicals include semi-volatile organic compounds (SVOCs), some of which have been shown to alter endocrine functionality, particularly at early developmental stages. SVOCs have the potential to accumulate in the indoor environment at high rates, which is correlated with high indoor exposures although it is not well quantified. The ExpoCast project is developing a model that predicts steady-state gas-phase concentrations (yₒ) of 871 ToxCast Phase I and II chemicals based on their physicochemical properties such as logP, vapor pressure, Henry’s law, boiling point, and molecular weight. The 871 chemicals is currently limited to those found in the indoor environment as per their respective chemical use categories found in the Aggregated Computational Toxicology Resource Database. The 74 chemical training set for this model is based on emissions data found in over 32 flooring materials (Wilke et al., 2004), including a natural and synthetic floor coverings, and adhesives. A linear regression yielded R2 - and p- values of approximately 0.3 and 2.0E-12, respectively, with logP and vapor pressure being the most significant predictors for yₒ. An indoor exposure prediction model (Little et al., 2012) was subsequently utilized in order to evaluate the robustness of the yₒ predictor for chemicals lacking analytical data in various articles of commerce. For any given SVOC, exposure calculations principally depend on yₒ as well as the surface area of its source material. In order to evaluate the indoor exposure model, high-throughput exposure predictions in mg/kg-BW/day were then compared with available oral equivalence values calculated from ToxCast high throughput screening assay data, available for 271 chemicals. Results show that both the yₒ and indoor exposure models tend to over-predict their respective values. Future work using Monte Carlo based uncertainty analyses and chemical domain of applicability testing are being pursued to better calibrate the model and reduce uncertainty.This abstract does not necessarily reflect EPA policy.
URLs/Downloads:
DOI: High Throughput Exposure Modeling of Semi-Volatile Chemicals in Articles of Commerce (SOT)