LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Medium: related to COD [ ]; DOC [ ]; test substance [X] as MBAS
water [X]; water-sediment [ ]; soil [ ]; sewage treatment [ ]
Degradation: 99.8% after 3 days (for sewage dose of 1.0 mg/L)
89.4% after 7 days (for sewage dose of 0.5 mg/L)
74.5% after 7 days (no sewage dose, but aerated)
40.7% after 7 days (no sewage, non aerated)
Results: readily biodeg. [ ]; inherently biodeg. [ ]; under test condition no
biodegradation observed [ ], other [X] primary biodegradation
Method: Samples from test flasks were taken at 12 hour intervals and the detergent
concentration expressed as methylene blue active substance was determined.
The initial concentration of detergent was 10 mg/L. The degradation of LAS
was evaluated in raw canal water and in canal water seeded with either 0.5
ml/L or 1.0 ml/L sewage from the Ismalia sewage treatment plant.
GLP: Yes [ ] No [X] ? [ ]
Test substance: Commercial LAS detergent (provided by Merck, Darmstadt, Germany);
likely average alkyl chain length = C11.6
Remarks: Medium was Ismailia Canal water (Cairo, Egypt). ABS and a 1:1 mixture of
ABS:LAS were also examined. Degradation of LAS was rapid, whereas
degradation of ABS and the 1:1 mixture of ABS/LAS was slower. In all
cases, aeration and addition of sewage microflora enhanced degradation.
Reference: Abdel-Shafy, H.I., Azzam, A.M. and El-Gamal, I.M. 1988. Studies on the
degradation of synthetic detergents by sewage. Bull. Environ. Contam.
Toxicol. 41:310-316.
Reliability: 2 Valid with restrictions
(l)
Type: aerobic [X]; anaerobic [ ]
Inoculum: adapted [ ]; non-adapted [X];
Concentration: 15 mg/L related to COD [ ]; DOC [ ]; test substance [X] HPLC
Medium: water [ ]; water-sediment [ ]; soil [ ]; sewage treatment [X]
Degradation: 95% after 28 days (LAS-A)
98% after 28 days (LAS-B)
Results: readily biodeg. [ ]; inherently biodeg. [ ]; under test condition no
biodegradation observed [ ], other [X]
Method: OECD303A coupled units test modified by AIS/CESIO "ad hoc" working
group.
GLP: Yes [X] No [ ] ? [ ]
Test substance: Two C10-13 LAS commercial products as described in the remarks.
Remarks: LAS-A, produced by the HF process, was 93% linear with 0.5% tetralins and
6.5% iso-branching and the following homologue distribution of the alkyl
chain: C10 15%, C11 34%, C12 31%, C13 20% (average alkyl chain length =
C11.56). LAS-B, produced by the AlCl3 process, was 98% linear with 0.5%
tetralins and 1.5% iso-branching and the following homologue distribution of
the alkyl chain: C10 15%, C11 29%, C12 32%, C13 24%, average alkyl chain
length = C11.65. HPLC methods specific to LAS were used to directly
measure the test substances (LAS as well as the biodegradable
intermediates). The ultimate biodegradation rates determined by HPLC are
>10% higher than those obtained using DOC determination. The studies
were conducted according to high standards and should be considered
reliable.
Reference: Cavalli, L., Cassani, G. and Lazzarin, M. 1996a. Biodegradation of linear
alkylbenzene sulphonate (LAS) and alcohol ethoxylate (AE). Tenside Surf.
Det. 33:158-165.
Reliability: 2 Valid with restrictions
(m)
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