Revised September 2014
The Council for LAB/LAS Environmental Research (CLER) is an organization of scientists and technical specialists representing member companies CEPSA Quimica, S.A. (Madrid), Huntsman Corporation (Houston), Quimica Venoco (Venezuela) and Sasol North America (Houston). CLER’s mission is to evaluate data, conduct research and distribute scientific information on the environmental safety of the world’s number one surfactant, linear alkylbenzene sulfonate (LAS) and the material from which it is produced, linear alkylbenzene (LAB).
For nearly fifty years, LAS has been the major surfactant used in laundry detergents and other cleaning products. Supporting this long history of safe use is an enormous database of environmental research on LAS which includes numerous peer-reviewed scientific publications and extensive data compilations. This research has looked at virtually every environmental compartment that might be exposed to LAS and considered all the components of commercial LAS.
Detergent components such as LAS typically go down the drain after use and flow into municipal sewage treatment plants or domestic septic systems. In some cases, more common in less developed parts of the world, disposal is directly into streams, rivers or the oceans.
Many studies have been conducted in the U.S. and in Europe on what happens to LAS during sewage treatment. Biological breakdown (biodegradation) of LAS actually begins in the raw sewage before it reaches the treatment plant. Once LAS reaches the sewage treatment plant, it is rapidly biodegraded and extensively removed. In modern treatment plants, LAS removal often exceeds 99%.
Treated water from sewage treatment plants is returned to streams, rivers or the oceans. LAS concentrations in the water and sediments of streams, rivers and oceans receiving treated water are very low and pose no risk to the organisms present. Any remaining LAS will continue to biodegrade until it is either incorporated into cell biomass or completely broken down (mineralized) to water, carbon dioxide and sulfate salts.
During sewage treatment, solids are separated from water, and some LAS adsorbs to the solids. These solids, called sludge, can be incinerated, placed in landfills or used as a soil conditioner or fertilizer. LAS does not harm crops planted in soil fertilized with sludge. Residual LAS continues to biodegrade so that yearly applications of sludge to agricultural lands do not cause any buildup of LAS.
LAS is also rapidly biodegraded and efficiently removed in septic systems, thereby protecting groundwater resources.
Commercial LAS contains small amounts of three constituents in addition to LAS itself: linear alkylbenzene (LAB), dialkyltetralin sulfonate (DATS) and methyl-branched alkylbenzene sulfonate (isoLAS). LAB, DATS and isoLAS have been shown to biodegrade rapidly and completely, and are safe for the organisms present in the environment.
Concerns have been expressed about detergent components and other materials that may become attached (adsorbed) to sediments deposited in oxygen free (anaerobic) environments where biodegradation is thought to proceed at a slower pace, if at all. Recent studies have shown that LAS can biodegrade under oxygen limited (anoxic) conditions and also under anaerobic conditions as well. Anoxic environments represent an intermediate environment between oxygen available (aerobic) and anaerobic conditions. Aerobic and anoxic conditions are more prevalent than anaerobic ones. Moreover, LAS levels in the environment are low, or not detectable, and pose no risk to the organisms present. Consequently, anaerobic conditions are not an issue for LAS environmental safety.
Over the years, the environmental safety and acceptability of LAS has been repeatedly confirmed in several major regulatory decisions including qualification as a surfactant raw material in the CleanGredient database, meeting the standards set by the U.S. Environmental Protection Agency Design for the Environment Program, a comprehensive assessment of the available health and environmental data on LAS by the international Organization for Economic Cooperation and Development ( OECD LAS SIDS Dossier), and the 2013 updated HERA Project health and environmental risk assessment of LAS use in household and cleaning products in Europe. In addition, the environmental safety of LAS has been reviewed in a comprehensive 2014 report on the “ Environmental Safety of the Use of Major Surfactant Classes in North America.”
The vast database on LAS, more extensive than on any other surfactant, provides complete and continuing assurance that LAS is environmentally safe and acceptable, and that LAS will be recognized as such for the foreseeable future.
Revised September 2014