LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

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OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS) termination. Sediment concentrations were monitored using LSC and verified with HPLC. GLP: Yes [X] No [ ] ? [ ] Test substance: LAS (Procter & Gamble), average alkyl chain length C11.4. The radiolabelled LAS was 3-dodecylbenzene sulfonate (DOBS; 95% purity) Results: There was a loss of between 15 and 78% of the LAS radioactivity over the duration of the test, which was attributed to mineralization of LAS by the worms and microorganisms present in the sediment (biodegradation). Results are therefore based on the average of day 0 and day 28 measured sediment concentrations. All results are shown in the following table. Sediment Concentration (mg/kg dw) Survival Endpoint NOEC LOEC EC20 EC50 Based on nominal values 100 150 90 136 Based on measured day 0 values 136 170 131 164 Based on mean of days 0 & 28 values Biomass Endpoint 81 110 73 105 Based on nominal values 100 150 108 144 Based on measured day 0 values 136 170 146 166 Based on mean of days 0 & 28 values 82 110 102 109 Remarks: LAS half-life in aerobic sediment was approximately 20 days. This is shorter than studies conducted in the same sediment without worms (halflife of 38 days), most likely due to increased bioturbation due to worm activity. No specific endpoint was particularly sensitive to LAS. Reference: Comber, S.D.W., Conrad, A.U., Hurst, K., Hoss, S., Webb, S., and Marshall, S. 2004. Chronic toxicity of sediment-associated linear alkylbenzene sulphonates (LAS) to freshwater benthic organisms. Manuscript in preparation. Reliability: 2 Valid with restrictions (s) Type : Artificial soil [ ]; Filter paper [ ]; Other [X] Spiked Sediment Species: Caenorhabditis elegans (Nematode) Endpoint: Mortality [ ]; Weight [ ]; Other [X] Survival, Fertility, Egg Production Exposure period: 3 days Results: LC50 (3 d) > 100 mg/kg soil dry weight NOEC = 100 mg/kg soil dry weight (egg production) Method: A 3 day chronic study was conducted using sediment spiked with coldmaterial LAS. Nominal concentrations were in the range of 10 to 1,000 mg/kg/dw. The test species is an infaunal bacterial feeder with a short life cycle, so 72 hours (3 days) is considered a chronic test. The nominal concentrations were 50, 75, 100, 150, 300, 600 mg/kg/dry weight and controls. The test sediment contained 44% sand, 48% silt, and 8% clay, with 2% organic matter. At the start of the test, ten juvenile worms of the first stage (270 ± 16 µm body length) were transferred to each test vial containing 0.75 g wet weight of spiked sediment mixed with 0.25 mL of a bacterial suspension. Five replicates were set up for each treatment, and the samples were incubated on a shaker at 20°C. After 72 hours the test was stopped by heat-killing the worms at approximately 50°C. The samples were mixed with an aqueous solution of rose Bengal to stain the worms for easier recovery. Sublethal toxicity endpoints were determined for growth based on the body length of the organisms, and fecundity by counting the number of eggs in the body of the test organism (egg production). The test was regarded as valid as the fertility of the test organisms in the control was ≥ 80%. UNEP PUBLICATIONS 220
OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS) GLP: Yes [ ] No [ ] ? [X] Test substance: LAS (Procter and Gamble), average alkyl chain length C11.4. Results: Results are shown in the following table. Nominal Sediment Concentration (mg/kg dw) Test Parameter NOEC LOEC EC10 EC30 Growth 200 300 275 Fertility 200 300 258 Egg Production 100 200 125 Remarks: For growth, with a low variability, an EC10 was chosen, whereas it was more appropriate to use an EC30 for the more variable parameters fertility and egg production. Egg production was the most sensitive endpoint. Toxicity values might be underestimated slightly, as threshold values were calculated using nominal concentrations (chemical analysis was only performed for selected test concentrations). The chemical analysis at the end of the test showed values 73 to 80% of the initial, nominal concentrations, which equates to mean exposure concentrations of 87 to 90% for the nematodes during the test. Reference: Comber, S.D.W., Conrad, A.U., Hurst, K., Hoss, S., Webb, S., and Marshall, S. 2004. Chronic toxicity of sediment-associated linear alkylbenzene sulphonates (LAS) to freshwater benthic organisms. Manuscript in preparation. Reliability: 2 Valid with restrictions (t) Type of test: Various types and durations of tests Results: The two articles compile the no observed effect concentration (NOEC) values for many tests conducted on an assortment of marine species. The following table shows the geometric mean NOEC values for each species for marine invertebrates, as well as one fish and two algae species. Genus (and species) Geometric mean NOEC (mg/L) Limanda (yokohamae) 0.05 Arbacia 0.45 Chaetopterus 0.45 Asterias 0.35 Mysidopsis (bahia) 0.12 Mysidopsis 0.20 Crassostrea (virginica) 0.025 Crassostrea 0.04 Mytilus (edulis) 0.025 Mytilus 0.04 Arcatia 0.30 Botrylloides 1.94 Molgula 0.90 Spisula 0.80 Botryllus 0.75 Laminaria 5.00 Dunaliella 0.11 UNEP PUBLICATIONS 221
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LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

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