LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
It was then treated in order to obtain the irreversibly adsorbed concentration
of LAS.
The test substance and sediment mixture were equilibrated for 6 hours on a
rotary shaker and then allowed to settle for 48 hours. Twenty eight washes
were made with deionized water to ensure the sediment did not release any
methylene blue material to the overlaying water. The residual concentration
was checked after every wash in the overlaying water of desorbed LAS using
the MBAS method. When an ~0 was observed, it was considered that the
irreversibly adsorbed quantity of LAS in sediment was attained. This
sediment was used in the experiment. The concentration of LAS in sediment
was measured by HPLC at 0, 45, and 220 days. Endpoints measured
included the number of cocoons, number of oocytes per cocoon, total
number of oocytes, period of embryonic development, percent of
degenerated cocoons, and percent of hatching worms.
GLP: Yes [ ] No [ ] ? [X]
Test substance: LAS solution (1000 mg/kg) mixed with 200 g dried sediment (from EniChem
Augusta Industriale S.A.)
Remarks: The LAS concentration in sediment used did not produce any effect on B.
sowerbyi during the 220 days of exposure. The authors conclude that LAS
absorbed on sediment has a much lower influence on the examined worms
than LAS dissolved in water. The intitial concentration of LAS in treated
sediments was 25.87 mg/kg (3.99 mg/kg in control). After 45 days, a
reduction of 62-63% of the nominal concentration was measured. After 220
days, the reduction reached 72%.
Reference: Casellato, S., Aiello, R., Negrisolo, P.A., and Seno, M. 1992. Long-term
experiment on Branchiura sowerbyi Beddard (Oligochaeta, Tubificidae)
using sediment treated with LAS (Linear Alkylbenzene Sulphonate).
Hydrobiologia 232:169-173.
Reliability: 4 Not assignable. Documentation is incomplete, including identification of
the structure, description of methods, lack of statistics, etc.
(r)
Type : Artificial soil [ ]; Filter paper [ ]; Other [X] Spiked Sediment
Species: Lumbriculus variegatus (Oligochaete)
Endpoint: Mortality [ ]; Weight [ ]; Other [X] Survival, Reproduction, and Growth
Exposure period: 28 days
Results: LC50 (28 d) ≥ 105 mg/kg soil dry weight (see table)
NOEC = 81 mg/kg soil dry weight
Method: A 28 day chronic study was conducted using sediment spiked with radiolabelled
material. The test species, Lumbriculus variegatus, is a true
sediment feeder (i.e., subsurface ingestion of sediment particles). 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. Twenty grams (wet weight) of the prepared sediment was added to
clean 60 mL glass vessels followed by 30 mL of groundwater drawn from
an aquifer. After 24 hours of equilibration, 10 mature Lumbriculus (ca. 15
mm in length, 8 mg dry weight) were added to each vessel. Vessels were
aerated for 5 minutes every day and the overlying water replenished with
distilled water every two days. Each test concentration was replicated 6
times. LAS concentrations were measured at 0 and 28 days. After 28 days
the sediment was removed and all live worms counted, blotted dry, and wet
weighed prior to air drying for 48 hours to a constant dry weight. Toxicity
endpoints included survival, reproduction and biomass. The mode of
reproduction (architomy) necessitates the treatment of survival and
reproduction as a single endpoint, i.e., number of organisms at test
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