Within the past 10‐15 years, synthetic detergents have almost completely replaced soap in the field of heavy‐duty washing products. One natural consequence of this has been the appearance of traces of detergent ingredients in sewage and, subsequently, in some surface and groundwaters fed by sewage effluents. The substance most frequently encountered in water supplies is the commercial anionic surface‐active agent, alkyl benzene sulfonate (ABS). This article briefly discusses studies done on health effects in humans and animals from ABS; the results of work with swine are discussed in some detail and are felt to be particularly relevant because of the similarity of this animal's digestive system to that of man. Conclusions indicate that humans and animals can tolerate relatively high concentrations of ABS in drinking water or food without any health effects. Several different sources of opinions are presented.