AN AQUATIC ENVIRONMENTAL SAFETY ASSESSMENT OF LINEAR ALKYLBENZENE

Linear alkylbenzene (LAB), the parent material from which the detergent surfactant linear alkylbenzene sulfonate (LAS) is manufactured, has the potential to enter the environment from several sources. Solubility, vapor pressure and soil partition measurements indicate that LAB would be distributed in air or adsorbed to soil or sediment. The material does not accumulate to significant levels in fish (BCF = 35) or undergo chemical or photochemical degradation in screening studies. LAB is readily biodegradable in natural waters with half-lives for various isomers and homologs in the 4-to 9-day range. LAB is not acutely toxic to a variety of aquatic species, other than Daphnia magna, within its water solubility range. For Daphnia, chronic studies in clean water systems indicate both growth and reproduction to be affected in the 10 to 20-mu-g/L range. LAB is substantially removed by typical sewage treatment plants. Receiving waters collected from sites receiving low sewage effluent dilution generally contain less than 1-mu-g/L. Based on the ratio of the chronic no-effect level for Daphnia to the environmental concentration, the conservative nature of selected monitoring sites i.e., providing low sewage effluent dilution) and the fact that LAB partitions strongly to particulates in the water column, adequate environmental safety margins exist for LAB.