LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Test Substances:
in simulated receiving water and soil environments at rates similar to that of
sulfophenyl carboxylate (SPC) intermediates of a standard LAS.
14
C-benzene ring labeled C12 LAS (97.5% radiochemical purity); 14 C-benzene
ring labeled iso-LAS of the following types (IA, 97.8% purity; IB, 77.6%
purity; IIA, 94.7% purity; IIB, 97.5% purity); 14 C-benzene ring labeled
DATS (97.3% purity), plus the non-labeled versions of the same.
Reference: Nielsen, A.M., Britton, L.N., Beall, C.E., McCormick, T.P. and Russell, G.L.
1997. Biodegradation of coproducts of commercial linear alkylbenzene
sulfonate. Environ. Sci. Technol. 31:3397-3404.
Reliability: 2 Valid with restrictions
(y)
Type: aerobic [X]; anaerobic [ ]
Method: OECD 301E. The study was designed to investigate the biodegradation of a
relatively high iso-branched form of commercial LAS. The test was a
prolonged batch-biodegradation experiment in which the material is kept
“alive” for 80 days and in which the test compound present in a mineral salts
medium is the sole carbon source. An enriched level of bacterial biomass,
three times the amount recommended, was added at the test start using an
inoculum obtained from the settled supernatant slurry solution of a fertile
soil, without any previous exposure to the test compound. LAS was
maintained by adding about 0 mg/L of fresh substance every four days for 80
days. After 80 days the test solution was sampled, centrifuged, sterilized
with HgCl2 solution and analyzed with a chemical specific HPLC method
with fluorescence detection.
Results: Results indicate a residual LAS amount of 1.5 mg/L and SPC intermediate
amount of 28.7 mg/L at the end of the 80 day study. Four distinct SPCs
originating from the linear components of LAS were formed from the
biodegradation experiment, and made up most of the organic residue. No
evidence of structures related to the iso-branched material was found in the
residue, therefore no accumulation of these materials is indicated. The isobranched
component of LAS and the corresponding SPCs mineralized at
rates as fast as the linear components.
Test Substances: Commercial LAS (HF type) with a C10-C13 alkyl chain and a linearity of
about 93%, with a low DATS content (