LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

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OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS) 2.2.7 Bioaccumulation The bioaccumulation potential of LAS has been investigated. Early studies, e.g., Kimerle et al. 1981, used 14C-ring labelled LAS and measured only total radiolabeled materials, likely including LAS metabolites, and thus limiting the conclusions that can be drawn specific to LAS. Tolls et al. (1997) conducted a series of experiments with fathead minnows (Pimephales promelas) according to OECD Guideline 305E protocols in which the limitations of the earlier studies were overcome. Individual LAS homologues were tested in flow-through exposures for up to 192 hours for the uptake phase, followed by a depuration phase in which fish were transferred to unspiked water. The resulting bioconcentration factors (BCFs) ranged from 2 L/kg (6-phenyl-C10 LAS) to almost 1000 L/kg (2-phenyl-C13 LAS), with BCF generally increasing with increasing alkyl chain length. BCF values were also calculated for a standard mixture (typical of LAS in European detergent formulations, average alkyl chain length = C11.6) and a representative environmental sample (filtered Mississippi river water, average alkyl chain length = C10.8). The respective BCFs were 87 and 22 L/kg, indicating that the bioconcentration potential of LAS is decreased by environmental processes such as biodegradation and absorption, which reduce aquatic concentrations (Tolls et al. 1997). These processes, as documented above, also preferentially remove longer alkyl chain length components, reducing the bioconcentration potential of the mixture fingerprint since the remaining lower alkyl chain materials have lower BCFs. 2.2.8 Other Information on Environmental Fate In the US, monitoring in 50 wastewater treatment facilities in 11 states showed average LAS levels in raw sewage ranged from 4.2 to 5.7 mg/L (McAvoy et al. 1993) while levels in raw sewage from five European countries ranged from 4.0-15.1 mg/L (DiCorcia et al. 1994, Waters and Feijtel 1995). US monitoring data indicated that LAS is largely removed in wastewater treatment plants, averaging over 99% removal in activated sludge, 98% for lagoons/oxidation ditches, 96% for rotating biological contactors and 77-82% for trickling filters (McAvoy et al. 1993, Trehy et al. 1996). Monitoring data from five European countries showed LAS removal in activated sludge treatment ranged from 98.5-99.9% (DiCorcia et al. 1994, Waters and Feijtel 1995) and averaged 92.9% in four trickling filter plants in the U.K. (Holt et al. 2000). Results of a mass balance study of an activated sludge treatment plant indicate that removal is primarily due to biodegradation with only about 20% of the influent LAS removed with the sludge (DiCorcia et al. 1994). In the US, average concentrations in river water below treatment plant mixing zones were generally below 50 µg/L for samples collected under low dilution conditions (McAvoy et al. 1993, Trehy et al. 1996). Tabor and Barber (1996) reported LAS at concentrations ranging from non-detect (
OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS) wastewater was discharged untreated, was 28 µg/L. Nishiyama et al. (2003) reported that the median LAS concentration in water from 4 rivers (7 sites) in Japan was 6 µg/L (range
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LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

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