LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
length) were added to each aquarium. Fish were screened from access to the
macroinvertebrates by a 60 mesh stainless steel screen and were fed a daily
supplement of frozen brine shrimp. Test duration was 28 days. Effects
monitored included population and community effects. Nominal
concentrations were confirmed with MBAS analysis. After 28 days the
vegetative shoots of Elodea were removed, the total length measured, and the
shoots were placed into aluminium dishes for determination of ash-free dry
weights.
GLP: Yes [ ] No [ ] ? [X]
Test substance: LAS; C 14 -LAS chain length C12 (91% purity) plus unlabeled LAS with
average chain length C11.6 (C10 9.7%, C11 27.9%, C12 54.4%, C13 8.0%; 95%
purity) (tested together)
Remarks: Dissolved oxygen concentrations ranged between 7.0 and 9.0 mg/L.
Temperature was maintained at 2°C and the mean pH was 8.1 ± 0.2. The
growth and productivity of Elodea was not significantly inhibited at the
highest concentration tested (4 mg/L) in Phase I. Growth throughout the 28day
exposure approximately doubled the initial biomass of the vegetative
shoots from a mean of about 37 mg ash-free dry weight to a mean of about
72 mg for the treatment concentrations. Similarly, Phase II experiments
resulted in an approximate doubling of the initial Elodea biomass in the
controls and the 3.75% effluent concentration, though the heavy growth of
attached bacteria and fungi (periphyton) that developed in the higher
concentrations effectively covered the growing surface of the Elodea shoots
resulting in progressively lower productivity in 7.5, 15 and 30% dilutions.
Reference: Maki, A.W. 1981. A Laboratory model ecosystem approach to
environmental fate and effects studies. Unpublished Internal Report,
Environmental Safety Department Procter and Gamble Company,
Cincinnati, Ohio.
Reliability: 2 Valid with restrictions
(p) (Lemna)
Species: Lemna minor (aquatic plant)
Endpoint: Biomass [ ]; Growth rate [ ]; Other [X] frond count
Exposure period: 7 days
Results: EC50 = 2.7 mg/L
NOEC = 0.9 mg/L (calculated as EC50/3); normalized to C11.6 = 1.1 mg/L
Analytical monitoring: Yes [X] No [ ] ? [ ]
Method: A 7-day flow-through growth inhibition test was developed using duckweed
(Lemna minor). Control water (carbon and reverse osmosis filtered well
water) and five concentrations of test material were delivered from diluter
mixing chambers to Pyrex glass exposure chambers at a rate of 1.5 L every
16 minutes (approximately 14 replacement volumes per day). At time 0,
each chamber received seven 2-frond, root excised duckweed colonies (four
replicates per treatment level). Plants were given continuous illumination at
3875 lux (360 foot candles) and temperature was maintained between 21 and
23 o C. Total hardness was 120-130 mg/L CaCO3 and pH was 7.2-7.6. The
number of fronds was recorded once every 24 hours for 7 days. LAS
concentrations were measured using the MBAS method.
GLP: Yes [ ] No [ ] ? [X]
Test substance: C10-14 LAS, average alkyl chain length 11.8, MW = 345, 27.3% active
Remarks: Results based on frond count were found to provide the most useful
information per unit of laboratory time. Other endpoints resulted in 7-day
EC50 values of 3.6 mg/L (dry weight), 4.9 mg/L (root length), and 4.8 mg/L
(growth rate/doubling time). Concurrent tests with bluegill sunfish (96-hr
LC50 = 1.7 mg/L) and D. magna (48-hr LC50 = 4.4 mg/L) indicate that
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