Quantitative relationships between interfacial properties and aquatic toxicity for dodecanol ethoxylates

The relationship between the acute toxicity on Daphnia magna of a series of nonionic surfactants, dodecanol ethoxylates, and the physical chemical parameters related to their surface activity (CMC, C-20 and A(min)) has been investigated. CMC is the critical micelle concentration of the surfactant, C20 is the surfactant concentration required to reduce the surface tension of the aqueous phase by 20 mN/m and A(min) is the minimum cross-sectional area of the surfactant at the surface of the aqueous phase. These parameters have been determined from surface tension measurements conducted in the same aqueous medium than toxicity tests. High correlation coefficients (r >= 0.95) have been obtained between the toxicity on Daphnia magna of dodecanol ethoxylates and their surface-active properties.