Relative Eye Irritation Potential of Nonionic Surfactants: Correlation to Dynamic Surface Tension

Abstract Ten nonionic surfactants, including five alcohol ethoxylates, were selected to test for correlations between measured eye irritation potential of surfactant solutions and a comprehensive set of surface tension measurements on the same solutions. The surfactants were evaluated in aqueous solutions at a concentration (0.2 M) chosen to represent the maximal use concentration in aqueous laundry and cleaning products. The low-volume eye test (LVET) was used to evaluate eye irritation potential of the surfactant solutions. Results were reported as maximum average scores (MAS) and medium days to clear (MDTC). The MAS values ranged from 0.0 to 13.3 (on a scale of 0-110) and the MDTC from 0 to 4 days. Based on these scores, the eye irritation potential of the surfactant solutions ranged from none to low. Analysis of variance revealed that the differences among the surfactant solutions in MAS scores were highly significant (p < 0.001). There were no significant regression correlations between MAS scores and any equilibrium surface tension property measured. However, there was a significant correlation (p < 0.02) between MAS scores and the maximal reduction in surface tension (surface tension effectiveness) measured under two dynamic conditions (1.0 and 0.25 s response time). This is the first report of a significant correlation between eye irritation potential and any surfactant property. Dynamic surface tension effectiveness may be predictive of the eye irritation potential of nonionic surfactants at the concentrations used in laundry and cleaning products.