Results from the SwedishNational ScreeningProgramme 2007Subreport 4: Linear alkylbenzene sulfonate (LAS)

LAS (linear alkylbenzene sulfonate) is an anionic sufactant mainly used in laundry- and dishwashingdetergents and lubricant additives. The annual amount used in Sweden is about 900 tonnes. As anassignment from the Swedish Environmental Protection Agency, IVL has performed a screeningstudy of LAS. The overall objective of the screening was to determine concentrations in a variety ofmedia in the Swedish environment. A national sampling program (50 samples) was combined withan extensive regional program administered by eight county administarive boards (72 samples).Sample types were waste water, sludge, storm water, ground water, surface water, soil and sediment.LAS was not found in surface waters, sediments or soil from background areas.LAS was found in the influents to all investigated sewage treatment plants (STPs). The medianconcentration was 360 µg/l. LAS was also found in all effluent waters from STPs. The medianconcentration was 2.7 µg/l. In 19 pairs of influent/effluent waters the removal efficiency was 95 -99.9%. The median concentration in sludge was 670 mg/kg DW. As an average 33% of the LASentering STPs ended up in sludge.LAS was found in traffic related storm waters (0.2 – 6 µg/l) and land fill lechates (0.58 – 1.2 µg/l).Sediments from the urban area Stockholm were contaminated with LAS (360 – 1 600 ng/g DW).Commercial LAS consists of a mixture of chain lengths ranging from C10 to C14. An alteration inthe distribution of chain lengths were noticed depending of sample types.The concentrations of LAS measured in sediments from recipients and urban areas (270-1 600ng/g DW) are lower than the PNEC-values, 8 100 ng/g DW and 4 900 ng/g DW for fresh watersediments and marine sediments respectively, found in the literature (Chapter 2.2). However, thesevalues have been derived from limited sets of data and some studies indicate that they might not beprotective.The concentrations of LAS found in surface waters from urban areas and industrial recipients werelower than reported PNEC-values derived from extensive sets of toxicity data. Thus, LAS is notexpected to cause adverse effects in the water phase of the recipients.