Assessing the effects of a C14-15 linear alcohol ethoxylate surfactant in stream mesocosms

Fish, benthic macroinvertebrate, and plant responses to 30-day exposures of C14-15 linear alcohol ethoxylate surfactant with an average of 7 mol of ethylene oxide (LAE) were measured in flowthrough stream mesocosms. Replicate stream mesocosms were treated in two experiments with concentrations of LAE ranging from 80 to 550 microg/liter. Macroinvertebrates were relatively insensitive with the exception of Simuliidae density which was significantly affected at 160 microg/liter. Fathead minnow (Pimephales promelas R.) reproduction was significantly reduced at >280 microg/liter and larval survival decreased significantly at 330 microg/liter. Growth and mortality of bluegill sunfish (Lepomis macrochirus L.) were not affected at the highest exposure concentration of 330 microg/liter in the first experiment. No ecologically significant effects were observed for vascular aquatic plants or periphyton. The laboratory and stream mesocosm results were similar with NOECs ranging between 80 and 550 microg/liter surfactant. The study provided data for an improved risk assessment of this nonionic surfactant, by reducing the uncertainty associated with extrapolation from laboratory data.