LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Daphnia magna
Average chain length 24 hour 48 hour
C4 (SØ Butyrate) 4 ~12,000 ~6,000
C5 (SØ Valerate) 5 ~12,000 ~5,000
C11 (SØU) 11 355 ± 150* 208 ± 85*
*Subsequent repurification of this sample yielded a product with the same isomeric composition but
with LC50 values over 1000 mg/L for daphnids (Swisher et al., 1976).
Analytical monitoring: Yes [X] No [ ] ? [ ] MBAS
Method: EPA-660/3-75-009 1975. Method for acute toxicity tests with fish,
macroinvertebrates and amphibians.
Acute toxicity tests were conducted on high molecular weight LAS,
individual pure homologues, non-linear LAS components (dialkyl tetralin or
indane sulfonates (DTIS), and model biodegradation intermediates
(sulfophenyl undecane, SØU) in order to determine whether biodegradation
decreases toxicity. In 250 mL beakers with 200 mL of well water of
approximately 250 mg/L hardness, ten Daphnia, less than 18 hours old, were
placed in each of the three beakers. No food was added for the duration of
the test.
GLP: Yes [X] No [ ] ? [ ]
Test substance: 1) High molecular weight LAS: Average chain length = 13.3; C11 1%, C12
8%, C13 52%, C14 39%
2) Individual LAS homologues of C10, C11, C12, C13, and C14
3) Nonlinear LAS components (DTIS)
4) Model biodegradation intermediates
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. Daphnia acute
toxicity tests on partially degraded LAS demonstrated that toxicity is
significantly lessened as LAS biodegraded. Because of the shorter than
normal study duration and smaller than standard number of Daphnia 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
B. Other aquatic invertebrates
(a)
Species: Gammarus pulex (amphipod)
Mysidopis bahia (mysid)
Panaeus duorarum (pink shrimp)
Results: EC50 (G. pulex) = 6.2 mg/L (25 records)
EC50 (M. bahia) = 1.7 mg/L (6 records)
EC50 (P. duorarum) = 49 mg/L (5 records)
Test Substance: C10-14 LAS (all LAS in range, including data for individual homologues)
Remarks: Geometric mean EC50 values for number of records listed for each species.
The interspecies variation decreases considerably when the geometric mean
value per species is calculated.
UNEP PUBLICATIONS 185