LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
soil microorganisms. The extracellular β-glucosidase activity was rather
insensitive to LAS (EC10, 47 mg/kg dry weight), whereas the basal soil
respiration was not inhibited even at 793 mg/kg dry weight. This was
interpreted as a combined response of inhibited and stimulated compartments
of the microbial community. The PLFA content showed no decrease even at
488 mg/kg.
Analytical monitoring: Yes [X] No [ ] ? [ ]
Method: The short-term effects of aqueous LAS on microbial parameters was tested in
a sandy agricultural soil that was incubated for up to 11 days. The assays
included 10 microbial soil parameters: ethylene degradation; potential
ammonium degradation; potential dehydrogenase activity; β-glucosidase
activity; iron reduction; populations of cellulolytic bacteria, fungi and
actinomycetes; the basal soil respiration; and the phospholipid fatty acid
(PLFA) content. Soil from the plough layer was sampled at an agricultural
field at Lundgaard, Denmark. The soil consisted of coarse sand (67%), fine
sand (16%), silt (8.6%), clay (6.2%), humus (2.7%) and had a total carbon
content of 1.5%. The soil had not been treated with sewage sludge and had
not been sprayed with pesticides in the last two years. For the experiments
with aqueous LAS, triplicate soil incubations were amended with the
appropriate LAS solutions to produce the LAS contents. The soils were
carefully mixed and incubated in the dark and duplicate soil samples for LAS
analyses were frozen at the beginning of the incubation period. EC10 and
EC50 values were calculated by a linear-interpolation analysis (ICp), which
was based on bootstrapping. The NOECs and LOECs were determined by
Dunnett’s test using a SAS analysis-of-variance procedure. Nominal
concentrations were control, 8, 22, 62, 174 and 488 mg/kg dw soil, except for
BR (control, 0.8, 8, 79 and 793 mg/kg dw soil). On average, 84 to 95% of
the nominal concentrations were initially recovered by the chemical analysis.
Nominal levels were used for the calculation of effect concentrations.
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%
Remarks: The study demonstrated that LAS inhibited specific compartments of the soil
microbial community. The lowest EC10 values for microbial soil parameters
were slightly higher than the predicted no-effect concentrations recently
derived for plants and soil fauna (~5 mg/kg dry weight). A subsequent study
(Elsgaard et al. 2001, Part 2) further indicated that the short-term effects
observed for aqueous LAS on soil microbiology were modified by the dosage
of LAS with sewage sludge and by a prolonged incubation time. The data
suggest that a terrestrial risk assessment based on short-term affects of
aqueous LAS fully encompasses the risk that may occur when LAS is applied
to agricultural soil by means of sewage sludge.
Reference: 1) Elsgaard, L., Petersen, S.O., and Debosz, K. 2001a. Effects and risk
assessment of linear alkylbenzene sulfonates in agricultural soil. 1. Shortterm
effects on soil microbiology. Environmental Toxicology and Chemistry
20:1656-1663.
2) 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. Well documented publication, no GLP, ECx
calculation not fully detailed.
(f)
Type: Outdoor experimental stream
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