A tiered approach for aquatic risk assessment of alcohol ethoxylates

An environmental risk assessment approach for alcohol ethoxylate (AE) mixtures was recently published which required the concentrations of the AE homologues in a mixture. The application of this approach can be limited in certain circumstances because AE homologue concentrations would generally not be available without environmental monitoring and would be difficult to estimate by exposure modeling. A tiered assessment approach was proposed in this study which required AE homologue concentrations only in the last tier. A key parameter in the tiered approach was based on Monte Carlo simulation in which simulated AE mixtures were decomposed into plausible combinations of homologues. The value of this parameter was determined so that the probability of false-negative conclusions in the tiered risk assessment approach was minimized. The use of the tiered approach was demonstrated.