LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
(2) Results
LAS was identified in 21% of the surface water samples and 100% of the bottom sediment samples.
Where detected, surface water concentrations ranged from 0.1 to 28.2 µg/L (mean = 2.21 ± 3.77 µg/L),
with the highest concentrations occurring near cities such as Minneapolis and St. Louis and concentrations
decreasing with increasing distance downstream. The average alkyl chain length for the dissolved LAS
was C11.1 (range C10.2-12.0).
Bottom sediment concentrations ranged from 0.01 to 0.95 mg/kg (mean = 0.23 ± 0.19 mg/kg) [one outlier
of 20 mg/kg from an effluent transport canal was excluded], with the highest concentrations occurring
downstream from Minneapolis, a large city located on a relatively small river. The average alkyl chain
length of the sediment associated LAS was C11.5 (range C10.7-11.9).
The data indicate that biodegradation and sorption are the main removal processes affecting dissolved LAS.
(3) Remarks
The aquatic NOEC is 270 µg/L, a conservative value based on C12 LAS which is the top end of the range
found in the environment. The mean surface water concentration measured in the Mississippi River in this
study is 2.21 µg/L.
NOEC values for sediment exposure are ≥81 mg/kg while sediment concentrations ranged from 0.01 to
0.95 mg/kg (mean = 0.23 ± 0.19 mg/kg).
V. Reliability
(1) Reliability Score 2 (Reliable with restrictions) because OECD standard test methods do not exist for
monitoring studies. However, this is a high quality study carried out with strict attention to accepted
analytical and sample collection procedures.
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