LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Remarks: Half-lives compare well with those for ultimate degradation in lab soil tests
(with ........14-C-evolution), indicating that the degradation of LAS does not
lead to the ... formation of significant levels of break-down intermediates in
soil.
The homologue distribution of LAS in soil suggests that removal represents
biodegradation rather than leaching.
Reference: 1) Holt, M.S., Matthijs, E. and Waters, J. 1989. The concentrations and fate
of linear alkylbenzene sulphonate in sludge amended soils. Wat. Res.
23:749-759.
2) Waters, J., Holt, M.S., Matthijs, E. 1989. Fate of LAS in sludge amended
soils. Tenside Surfactants Detergents 26(2):129-135.
Reliability: 2 Valid with restrictions
(d)
Type: Laboratory
Radiolabel: Yes [ ] No [X] ? [ ]
Concentration: 8 to 488 mg/kg
Soil Composition: Coarse sand 67%, fine sand 16%, silt 8.6%, clay 6.2% and humus 2.7%
Organic Carbon: 1.5%
Method: LAS mixed with sewage sludge was applied to sandy agricultural soil and
incubated for up to 8 weeks. Various microbial soil parameters were
measured (see Section 4.4). LAS was quantified after methanol extraction
using HPLC.
GLP: Yes [ ] No [ ] ? [X]
Test Substance: C10-13 LAS obtained as an aqueous sodium salt solution with a LAS content
of 16.1% (w/w), NA-LAS average molecular weight = 342 g/mol,
distribution: C10 14%, C11 34%, C12 31%, and C13 21%.
Results: For nominal concentrations of 8 to 62 mg/kg, the depletion of LAS after 2
weeks was more than 73%. At 488 mg/kg, only 15% depletion occurred. It
is possible that this high LAS level may have inhibited microbial activity or
caused a prolonged log phase to occur.
Reference: Elsgaard, L. Petersen, S.O. and Debosz, K. 2001b. Effects and risk
assessment of linear alkylbenzene sulfonates in agricultural soil. 2. Effects
on soil microbiology as influenced by sewage sludge and incubation time.
Environmental Toxicology and Chemistry. 20:1664-1672.
Reliability: 2 Valid with restrictions
(e)
Type : Field trial [X]; Laboratory [X]; Other [ ]
Radiolabel: Yes [ ] No [X] ? [ ]
Soil Content: Clay 1.8 - 4%, Silt 7.6 - 18.5 %, Sand 77.1 - 95.5%
Organic Carbon: Ranged from 0.9 - 1.79%
Soil pH: 5.2 – 6.8
Dissipation time: DT50: 3 days (lysimeters)
DT50: 7 days (field trials)
Method: Sewage sludge containing LAS was added to four cultivated sandy soils with
low amounts of organic matter in field trials and lysimeter studies. The field
trial lasted one year. For the lysimeter studies, undisturbed soil columns
were taken from the corresponding field sites.
GLP: Yes [ ] No [ ] ? [X]
Test substance: Marlon A350 (CAS #68411-30-3) C10-13 LAS, average alkyl chain length =
11.6; activity: 50%
Remarks: LAS are mobile in all four soils tested. They were detected down to a depth
of 30-40 cm after being applied at the surface. After one week, a
concentration of 500 mg/kg was measured in the 0-5 cm layer, which
corresponds to 23% of the the total LAS. In the 5-10 cm layer, the
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