The results of a monitoring study at ten U.S. sewage treatment plants have confirmed the environmental safety of linear alkylbenzene sulfonate (LAS) and dialkyltetralin sulfonate (DATS), a co-product of LAS manufacturing. In this study, the levels of LAS, DATS and their biodegradation intermediates were measured in raw sewage coming into treatment plants, treated water leaving the plants, and river water both upstream and downstream of the mixing zones where treated water is discharged into rivers and streams. This is the first study to measure real world levels of DATS and DATS intermediates in these environments.
The results of this study demonstrate that, due to effective biodegradation and removal in sewage treatment, concentrations of LAS, DATS and their biodegradation intermediates are very low (parts per billion range) in the rivers and streams receiving treated water. A previously reported study (Rapaport et al., 1992) has demonstrated that these trace levels of LAS, DATS and their intermediates pose no risk to aquatic or other environmental organisms. Other studies (Nielsen et al., 1992, 1993) have demonstrated that these trace levels will continue to biodegrade until they have mineralized into carbon dioxide, water and sulfate salts, materials harmless to the environment.
The monitoring study was sponsored by the Council for LAB/LAS Environmental Research (CLER) and the Procter & Gamble Company. The report has just been accepted for publication and will appear in the March, 1996, issue of the technical journal, Environmental Toxicology and Chemistry.