LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Remarks: The length of the alkyl chain is the most important factor influencing acute
toxicity, which increases as the alkyl chain increases. These longer alkyl
chain homologues are the first constituents of the LAS mixture to degrade.
The nonlinear components (DTIS) showed 1/2 to 1/10 the toxicity of LAS
with the same carbon chain length. Toxicity of biodegradation
intermediates is significantly less than the parent LAS. Because of the
shorter than normal study duration and smaller than standard number of
fish per concentration, the reliability of the absolute values cannot be
assessed. However, the study is considered reliable for the trends in the
data because the homologues were tested under identical conditions.
Reference: Kimerle, R.A. and Swisher, R.D. 1977. Reduction of aquatic toxicity of
linear alkylbenzene sulfonate (LAS) by biodegradation. Water Research
11:31-37.
Reliability: 2 Valid with restrictions
4.2 ACUTE TOXICITY TO AQUATIC INVERTEBRATES
A. Daphnia
(a)
Type of Test: Static [X]; semi-static [ ]; flow-through
Open-system [X]; closed-system [ ]
Species: Daphnia magna (Crustacea)
Exposure Period: 48 hours
Effect Criteria: Immobility
Results: EC50 = 1.62 mg/L; The number of immobile animals at each concentration is
shown in the following table:
Concentration of test substance (mg/L)
Time (h) 0 3.2 5.6 10 18 32 56 100
0 0 0 0 0 0 0 0 0
24 0 0 0 0 0 0 12 20
48 0 0 0 1 a 6 a 12 a 20 20
a Condition of mobile animals was impacted as compared to the controls in a dose-responsive manner.
Analytic Monitoring: Yes [X]; No [ ]; ? [ ]
Method: OECD Guideline 202. Seven concentrations (3.2, 5.6, 10, 18, 32, 56, and
100 mg/L) plus controls were tested. The dilution water was DSWL
water, prepared from ground water. Four beakers containing five Daphnia
each were used for each test or control solution. Daphnia were less than 24
hours old at test initiation. A fifth beaker with 100 mg/L solution and five
Daphnia were added 24 hours after initiation. Test and control solutions
were not renewed and the Daphnia were not fed. Dissolved oxygen and pH
were measured at 0 and 48 hours in all concentrations, as well as at 24 hours
in the 100 mg/L chambers 24 hours after initiation because of total
immobility observed at that level. Dissolved oxygen ranged from 8.7 to 9.6
mg/L and pH ranged from 7.9 to 8.1. Water hardness was 215 mg/L as
CaCO3. Test temperature was maintained at 20 ± 1°C under a 16:8
(light:dark) cycle. The chambers were not aerated. Immobile animals were
counted at 24 and 48 hours. Samples for analysis of each concentration were
taken at 0, 24, and 48 hours. This is a key study for aquatic toxicity to
invertebrates (see SIAR Table 10).
GLP: Yes [X]; No [ ]; ? [ ]
Test Substance: LAS; 87.85% activity
Remarks: A 24 hour EC50 of 3.58 mg/L and a 48 hour NOEC of 0.379 mg/L (both
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