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EC number: 270-115-0
CAS number: 68411-30-3
A series of studies are used to
characterize the long-term toxicity of LAS to aquatic invertebrates. In
the key study (Maki 1977; van de Plassche et al 1999), the toxicity of C11.8LAS
was evaluated in a 21-day survival and reproduction test with Daphnia
magna. Four replicates per concentration, five organisms per
replicate, were tested in a flow-through system. Mean measured
concentrations were 0.32, 0.59, 1.18, 2.52, and 4.85 mg/L C11.8LAS
as active ingredient. Survival was monitored at 24-hr, 96-hr, 7 days and
daily thereafter. Reproduction was monitored beginning with the
production of the first brood on day 7 or 8, and daily thereafter.
Results, based on the mean measured concentration of the active
ingredient, indicate that the 21-day NOEC was 1.18 mg/L. The 21 day LC50was
1.67 mg/L, while the EC50s, based on total young production,
average brood size, and percent days reproduction occurred, were 1.50,
2.30, and 2.31 mg/L, respectively. These results were then normalized to
a C11.6LAS according to the methods of van de Plassche et al.
(1999), and the final NOEC value is 1.41 mg/L.
In another study (Taylor 1984;
van de Plassche et al 1999), a 7 day chronic toxicity test on C11.8LAS
was conducted with Ceriodaphnia sp. under semi-static conditions.Ceriodaphnia
were fed either a yeast diet, or an algae/trout chow diet. The test
medium was renewed three times in the seven days. Nominal test
concentrations were 0, 0.5, 1, 2, 3.5, 5 and 7 mg/L of active
ingredient. The resultant 7 day LC50values were 5-7 mg/L for
both diets. The no effect concentrations differed between diets. The 7
day NOEC for the yeast diet was 0.5 mg/L (based on reproduction) while
the 7 day NOEC for the algae/trout chow diet was 5 mg/L (based on
mortality and reproduction). When normalized to a C11.6LAS,
the lowest NOEC is 0.59 mg/L.
In the third study (Maki 1978,
1981; van de Plassche et al 1999), effects on the midge were examined.
Groups of P. parthenogenica were exposed for 28 days to
concentrations of 0.5, 1.0, 2.0, or 4.0 mg/L (nominal) of LAS. The LOEC
was 4 mg/L based on survival and reproduction, and the NOEC was 2.0
mg/L. When normalized to C11.6LAS, the NOEC value becomes
The chronic toxicity of C12.3LAS
was evaluated in a 2 day whole life cycle bioassay on the rotifer, Brachionus
calyciflorus (Procter & Gamble 1996; van de Plassche et al 1999).
Six newly hatched rotifers (<3 hours old) were placed in each replicate
beaker, and exposed to C12.3LAS for 48 hours. Results were
based on the total number of live, swimming organisms (both adults and
offspring) and measured concentrations. The resultant EC10value
was 1.18 mg a.i./L, the EC20was 1.4 mg a.i./L, and the EC50was
2.0 mg a.i./L. When normalized to a C11.6LAS, the EC10value
becomes 1.69 mg/L.
Finally, the chronic toxicity of
C12LAS was determined in a 32 day test (Versteeg 2001;
Versteeg and Rawlins 2003; van de Plassche et al 1999) with three
aquatic invertebrates (Corbicula, Elimia, Hyalella). The
invertebrates were caged in the tail pools of an environmental stream
mesocosm study of C12LAS. Toxicity was based on water
concentrations at which adverse effects were observed. Results were also
calculated based on the tissue concentrations at which adverse effects
were observed. All invertebrates were exposed to nominal concentrations
of 0, 0.15, 0.30, 1.0, and 3.0 mg a.i./L. As mean measured
concentrations were 84-99% of nominal, results are based on measured
concentrations. On days 0, 8, 16, and 32, the invertebrates were
examined for growth and survival. The results can be summarized as
follows (all normalized to C11.6): For Corbicula, the 32 day
EC20was 0.39 mg/L based on growth (length), for Elimina,
the 32 day NOEC was 4.15 mg/L based on survival and for Hyalella the
24 day EC20was 1.36 mg/L based on survival.
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