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EC number: -
CAS number: -
The cell densities and percentage inhibition
of growth values from the exposure of Desmodesmus subspicatus to
the test material during the range-finding test are given in Table 1
attached below. The results showed no effect on growth at the test
concentrations of 0.10, 1.0, 10 and 100 mg/l. Based on this information
a single test concentration of six replicates, of 100 mg/l was selected
for the definitive test. This experimental design conforms to a "limit
test" to confirm that at the maximum test concentration given in the
OECD/EEC Test Guidelines no effect on growth was observed.
Cell density values determined at each
sampling time and pH values at 0 and 72 hours are given in Table 3
(attached below). Daily specific growth rates for the control cultures
are given in Table 4 (attached below). Growth rate and yield values for
the control and test cultures after 72 hours and percentage inhibition
values are given in Table 5 (attached below).
The following data show that the cell
concentration of the control cultures increased by a factor of 58 after
72 hours. This increase was in line with the OECD Guideline that states
the enhancement must be at least by a factor of 16 after 72 hours.
Mean cell density of control at 0 hours:
4.44 x 103 cells per ml
A study was performed to assess the effect of the test material on the
growth of the green alga Desmodesmus subspicatus. The method
followed that described in the OECD Guidelines for Testing of Chemicals
(2006) No 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition
Test" referenced as Method C.3 of Commission Regulation (EC) No 440/2008
and further modified following the OECD Guidance Document on Aquatic
Toxicity Testing of Difficult Test Substances and Mixtures with regards
to coloured test substances.
Following a preliminary range-finding test, Desmodesmus subspicatus
was exposed to an aqueous solution of the test material at a
concentration of 100 mg/I (six replicate flasks) for 72 hours, under
constant illumination and shaking at a temperature of 24 ± 1°C. Samples
of the algal populations were removed daily and cell concentrations
determined for each control and treatment group, using a Coulter®
Multisizer Particle Counter.
Due to the coloured nature of the test
solutions prepared the study was conducted using a modified algal
inhibition test method with increased light intensity and decreased test
volume in order to minimise the effects of light adsorption by the test
material at the wavelengths required for photosynthetic growth.
Exposure of Desmodesmus subspicatus to the test material gave EC50
values of greater than 100 mg/I and correspondingly the No Observed
Effect Concentration was 100 mg/l.
It was considered unnecessary and
unrealistic to test at concentrations in excess of 100 mg/l. Analysis of
the test preparations at 0 and 72 hours showed measured test
concentrations to be near nominal and so the results are based on
nominal test concentrations only.
The effect of the test material on the growth of Desmodesmus
subspicatus has been investigated and gave EC50 values of greater
than 100 mg/l. Correspondingly the No Observed Effect Concentration was
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