Physicochemical Property Modules

Chemical properties related to biological activity are receiving increased attention for designing out the inherent hazards of a chemical. Of the physicochemical properties, there are several that are especially important to estimating hazards and risks. They each have significant roles in exposure or hazard estimations. They are being explored in models and new tools for predicting the toxicity of chemicals. It is important to note that the importance of understanding the physiochemical properties of a chemical is due to the fact that these chemicals must interact with living systems in order to be considered toxic, and so recalling some basic physiology and biochemistry principles are important to putting together these chemical properties with why they impact living systems. 

Can chemical properties predict the inherent nature of the molecules and can they serve as a guideline to reduce hazard? To address this question, a group of researchers from Yale University performed an analysis to see if toxic compounds share similar physiochemical properties. They were motivated to explore if compounds with established toxicity would have similar property distribution. The study analyzed over 550 commercial chemicals classified as toxic by the EPA, including chemicals from various industry sectors including manufacturing, metal and coal mining, hazardous waste treatment, and electric utilities. After applying mathematical algorithms, the distribution of physiochemical properties of these toxic compounds was different than control group made of chemicals listed as benign by the EPA.  This study provides missing link that connects physiochemical properties with toxicity, and confirms that classification of highly toxic compounds is indeed possible by only couple of quantifiable parameters. This breakthrough became a stepping stone in the research which was proposed by Molecular Design Research Network (MoDRN) to develop property based toxicity prediction tools. Computational sciences can serve as a starting point, and rests on three pillars including chemical structure, dynamics, and reactivity for building predictive models.

Video: Dr. Jakub Kostal, Associate Research Scientist, The George Washington Unversity and CSO of Sustainability A to Z

If you are trying to make a decision without testing every possible endpoint and therefore without full knowledge, there are a variety of tools that you can use to fill data gaps. EPA has developed a number of “screening-level” tools that allow estimations in the absence of measured data. These tools generally use chemical structure and structure-activity relationships (SARs) to estimate the properties of the substance. These are not the only tools and, are not necessarily the best tools, but they are quite effective, they are free, and are certainly sufficient for beginning your process for designing safer chemicals. 

The following MoDRN:U Modules were developed that address Physicochemical Properties:  

This material is based upon work supported by the NSF Division of Chemistry and the Environmental Protection Agency under Grant No. 1339637.