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Computational prediction of dermal diffusivity for large number of chemicals – challenges and applications
Citation:
Evans, M. Computational prediction of dermal diffusivity for large number of chemicals – challenges and applications. Society of Toxicology, San Antonio, Texas, March 11 - 15, 2018.
Impact/Purpose:
The principal route of exposure for multiple consumer products is through skin. The skin is a multi-layered organ, one that is both complex to describe mathematically and covers a large surface of the body. There are several constants used to describe dermal absorption: diffusion across the top layer of skin, chemical solubility between vehicle and skin, chemical molecular weight, and lipophilicity (solubility in fat). Despite the potential importance of the skin as a route of exposure, dermal exposure presents challenges that must be addressed for a successful predictive strategy. The application of chemical physical knowledge to the quantitative prediction of dermal absorption will be the major goal of this project.
Description:
The assessment of risk from dermal exposure for thousands of chemicals, such as consumer products, due to their potential to enter the environment as contaminants is a daunting task. A strategy has been developed to integrate high-throughput technologies with toxicity, known as Toxcast. For a growing number of consumer products, dermal application is the major route of exposure. Dermal modeling has estimated penetration using diffusivity as the key physical characteristic for the large surface area covered by skin. Diffusion is related to chemical-physical characteristics such as lipophilicity, molecular size and chemical structure. Diffusivity determines the amount of time taken for dermal penetration to start, also known as lag time and is determined experimentally. Therefore, our ability to calculate diffusivity will enhance our strategy to prioritize chemical penetration based on a chemical’s ability to enter the skin. One of the challenges for prioritization can be potentially addressed by identifying chemicals that penetrate quickly by using the lag time parameter. This talk presents an overview for approaches taken to examine diffusion estimates based on chemical properties. (This abstract does not reflect US EPA policy).