This article puts in perspective various questions concerning the environmental impact of alkybenzene sulfonates (ABS). Several points which are frequently overlooked or misunderstood are clarified:1.Except for the nuisance aspects of its foaming tendency, ABS entering the environment as a component of household sewage is insignificant relative to other pollutants.2.Any negative impact that ABS has—foaming, possible interaction with living organisms—comes from its surface active character. When it biodegrades sufficiently to lose its surface active character, it becomes innocuous. Hence, only “primary” biodegradation rates are important.3.Linear ABS (LAS) biodegrades much faster than highly branched ABS (BAS). However, they both eventually completely degrade in an aerobic environment.4.Neither BAS nor LAS degrade when the sewage does not receive adequate aerobic sewage treatment either in a treatment plant or in the receiving water. Therefore, in localities without adequate aerobic sewage treatment, there is no environmental incentive to use LAS in preference to BAS.5.Realistic laboratory tests mirror the sewage treatment process. It is not reasonable, except for screening purposes, to run biodegradation tests in the absence of sewage.6.Slight variations in the LAS structure—isomer distribution, modest branching—do not affect its biodegradation in realistic tests.7.The important criteria for a country contemplating a switch from BAS to LAS are the concentration of ABS found in receiving waters and the adequacy of sewag