Predictive Study of Eye Irritation Results Obtained from the STE Method Using Hansen Solubility Parameters

For animal protection, various studies on alternatives to safety tests in animals are being conducted. The short-time exposure (STE) method is described in the Organization for Economic Cooperation and Development Test Guideline 491 as an alternative to eye irritation animal testing. However, its accuracy and labor investment can be improved if the results can be predicted before the experiment. This study evaluated whether Hansen solubility parameter (HSP) values can be used to predict STE results. An HSP sphere was created based on the HSP values and STE results of 48 substances. Substances inside and outside the sphere were designated as dangerous and safe substances, respectively. The safety of each test substance was predicted by comparing the center point (R0) of the sphere with the relative energy difference, i.e., the ratio of each test substance (Ra). The accuracy, false-negativity, and false-positivity of the “irritant” and “non-irritant” designations, as determined by the STE results and Hansen sphere, were 91.7% (44/48), 4.8% (1/21), and 11.1% (3/27), respectively. These results indicate that HSP values can be used to predict STE results with high reproducibility, thereby evaluating the safety of the substances.