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EC number: 221-117-5
CAS number: 3007-53-2
The influence of the test substance on the growth of the freshwater algae Pseudokirchneriella subcapitata KORSHIKOV was assessed in a static dose response test according to OECD 201 (2006). The 72-hour ErC50 was determined to be 0.805 mg test item/L, the 72-hour NOErC was determined to be 0.351 mg test item/L and the associated 72-hour EC10 was determined to be 0.435 mg test item/L. All values were based on geometric mean measured concentrations.
The toxicity of the test substance to
the freshwater alga Pseudokirchneriella subcapitata KORSHIKOV was
determined according to the principles of OECD 201 (2006) and the
Commission Regulation (EC) No 761/2009/C3 (2009) under GLP conditions.
The aim of the study was to assess the effects on growth rate and yield
over a period of 72 hours. The study was conducted under static
conditions. This study encompassed 6 treatment groups (5 dose rates of
the test item, control) with three replicates per test concentration and
six replicates for the control. At test start 100 mL of the test
concentrations were inoculated with 5000 algal cells per mL test medium
and defined volumes of the algal suspensions were sampled after 0, 24,
48 and 72 hours for determination of cell densities by
spectrophotometrical measurement. The samples of the test media sampled
at the start and at the end of the test after 72 hours of exposure were
analyzed via capillary gas chromatography - mass spectrometry (GC-MS).
The nominal test concentrations of 0.46, 1.0, 2.2, 4.6, 10 mg test
item/L and a control are corresponding to geometric mean measured
concentrations of 0.35, 0.82, 1.80, 3.62, 8.45 mg test item/L and
control (0 mg test item/L). The measured concentrations of the test
substance in the test water were in a range of 74 - 84 % of the nominal
concentration at start of exposure. After 72 hours, the measured
concentrations remained within ± 20 % of the initially measured
concentration in test groups > 1 mg/L. In the lower test groups, > 20 %
of the test substance was lost in the algae inoculated samples. The
decrease at the end of exposure was most likely due to binding
(adsorption) of the test substance to the growing algal biomass in the
lower concentrations. To evaluate adsorption to algae, additional
samples were analyzed from the uninoculated replicate 0 of each test
group and the control at the end of the exposure (72 h). All
uninoculated replicates were within ± 20 % of the initially measured
concentrations. OECD 201 states that the alga growth inhibition test is
a more dynamic test system than most other short term aquatic toxicity
tests. Disappearance of the test substance from solution by adsorption
to the increasing algal biomass does not mean that it is lost from the
test system. Consequently, the results demonstrate the consistency of
test substance concentrations over the defined exposure period and the
geometric mean measured concentrations calculated using the uninoculated
replicates were used to evaluate the results.
The following effect concentrations
(mg/L) were obtained after 72-h based on nominal concentration: The
72-hour ErC50 value was determined to be 0.99 mg test item/L and the
72-hour EyC50 was determined to be 0.629 mg test item/L. The 72-hour
NOErC and the 72-hour NOEyC were determined to be 0.46 mg/L and greater
than 0.46 mg test item/L, respectively and the associated 72- hour LOErC
and LOEyC were determined to be 1 and 0.46 mg/L, respectively.
The following effect concentrations
(mg/L) were obtained after 72-h based on geometric mean measured
concentration: The 72-hour ErC50 value was determined to be 0.805 mg
test item/L and the 72-hour EyC50 was determined to be 0.494 mg test
item/L. The 72-hour NOErC and the 72-hour NOEyC were determined to be
0.351 mg/L and greater than 0.351 mg test item/L, respectively and the
associated 72- hour LOErC and LOEyC were determined to be 0.82 and 0.351
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