LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Method: Tests were conducted as an aqueous fraction in the presence of sediment.
Natural stream sediments (71% clay, 19% fine silt, 4% medium sand, 6%
fine sand) were collected from a pristine site in Rapid Creek, SD. Before
testing, wet sediment was autoclaved for 40-60 minutes to reduce microbial
populations and minimize initial rates of surfactant biodegradation. LAS was
added to a sediment slurry at a nominal concentration and stirred overnight,
then 350 g was poured into each test chamber and allowed to settle. The
organic carbon content of the test sediment was 4.2% prior to testing. A
flow-through diluter system delivered test material in water to glass
containers with 120-140 cm 2 bottom surface area each. Test concentrations
were control, 8, 42, 146, 319, and 993 ppm. Intact egg masses were
incubated in Petri dishes containing 20-30 mL of dilution water at 22 °C
until hatching commenced. Newly hatched larvae were allowed to mature
72 hours before testing. Twenty larvae were randomly distributed to each
duplicate test chamber for each of five test concentrations plus the controls.
Larvae were fed daily until emergence of the first adult in each chamber.
Tests were continued until each midge emerged as an adult or larvae were
determined to be dead. The number of winged adults was recorded daily.
The average test duration was 24 days. Total hardness, pH, dissolved
oxygen, and temperature were monitored frequently during the test.
GLP: Yes [ ] No [] ? [X]
Test substance: C11.8 LAS; 30.4% activity; mean molecular weight = 346
Remarks: Adults typically emerged 12-14 days after hatching. Control values for adult
emergence were similar to or exceeded the historical average observed in
their laboratory (>90%). Percent emergence was 98, 95, 90, 90, 90, and 73
for the control, 8, 42, 146, 319, and 993 ppm concentrations, respectively.
For comparison, additional flow-through studies were conducted without
sediment (see 4.5.2 (o)). Results indicate that sorption onto sediment
significantly mitigates LAS bioavailability.
Reference: Pittinger, C.A., Woltering, D.M., and Masters, J.A. 1989. Bioavailability of
sediment-sorbed and aqueous surfactants to Chironomus riparius (midge).
Environ. Toxicol. Chem. 8:1023-1033.
Reliability: 2 Valid with restrictions.
4.6 TOXICITY TO TERRESTRIAL ORGANISMS
4.6.1 TOXICITY TO SOIL DWELLING ORGANISMS
(a)
Species/Endpoints: See table
Results: The following table shows the available NOEC, EC10 and EC50 values for
eleven soil dwelling invertebrate species (in mg/kg dry weight).
Species Endpoint NOEC EC10 EC50
Eisenia foetida Reproduction 383 558
Lumbricus terrestris Weight 667
Aporrectodea caliginosa Reproduction 14 129
Aporrectodea longa Reproduction 27 137
Folsomia fimetaria Reproduction 96 442
Folsomia candida Reproduction 18 91
Hypoaspis aculeifer Reproduction 81.7 236
Enchytraeus albidus Reproduction 6.2 40.5
Platynothrus peltifer Reproduction 320 467
Isotoma viridis Growth 41
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