Acute and chronic aquatic toxicity structure–activity relationships for alcohol ethoxylates

Acute and chronic toxicity tests using the cladoceran Daphnia magna were conducted on several alcohol ethoxylate surfactants. Exposure and homologue distributions were confirmed using specific analytical methods. These data were used to test currently available acute structure–activity relationships (SARs) and to develop a new chronic SAR to extrapolate test data to effluent or receiving water mixtures. Existing acute SARs adequately predicted the toxicity of these materials with an r 2 of 0.96 based on alkyl chain length and number of ethoxylates and 0.98 based on log K ow. The additional chronic toxicity data allowed for development of a chronic SAR based on log K ow and produced an r 2 of 0.93. Slopes of new and published acute, chronic, and mesocosm SARs based on log K ow ranged from −0.61 to −0.87. These new data and refined SARs will assist in the toxicity prediction of mixtures in the environment.