Chemical, cosmetic, and other personal care companies must follow strict guidelines in order to manufacture and market their products globally. For example, a European regulatory standard called REACH supports better protection of both human and environmental health and holds manufacturing companies responsible for recognizing and identifying potentially-harmful chemical properties. Similarly, the FDA regulates cosmetics available to consumers in the United States. Unfortunately, determining whether chemical compounds—and thus emerging products—are safe for human application usually necessitates testing on either animal or human skin. And incomplete knowledge of the biological and/or chemical mechanics behind these compounds has limited prior efforts to simulate alternative methods of testing.
Researchers from the James L. Winkle College of Pharmacy at the University of Cincinnati, in collaboration with colleagues from Goethe University Frankfurt in Germany, are hoping to change the standards of cosmetic testing. They are developing a mathematical model to understand how chemical compounds are transported through—and consequently affect—biological tissues, such as skin.
This model will allow scientists to experiment with and test chemical compounds virtually, says Gerald Kasting, lead researcher and professor of pharmaceutical sciences at the University of Cincinnati. Unlike prior simulation techniques, Kasting et al.’s model is predictive. In order to craft the model, the researchers used data from previous testing of chemical compounds on human skin, which thoroughly measured if and how much the compounds in question were absorbed by the skin. The test also measured how the compounds traveled within the dermal layer directly below the skin’s surface, and whether the chemicals were likely to produce an allergic reaction.
Using that data, the researchers developed equations identifying whether certain chemicals will cause a reaction or harmfully penetrate the skin. They then created a model that predicts how human skin would react to tens of thousands of other compounds that hadn’t previously been tested, including fragrances and preservatives to which many consumers might be sensitive. The resulting model can predict the behaviors of 30,000 or so compounds based on the results of a test subset of only 200, says Kasting. Read more of his explanation here.
Although the research is still in its early stage and the model is likely not yet developed to the extent that it can single-handedly influence chemical safety guides, the study offers a starting point for identifying which chemical compounds will cause skin reactions without actually causing those reactions through testing. The research may eventually offer a means of accurately and effectively evaluating consumer products, eliminating the need for human and animal testing.
Kasting’s prior work with mathematical models for skin permeability can be viewed here.
||Lina Sorg is the associate editor of SIAM News.