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EC number: 945-888-9
CAS number: -
Table 1: Mean growth rate and percent
inhibition compared to the control
Nominal loading rate
Number of replicates
Mean growth rate
Mean inhibition of growth rate
- 1.97 %
Table 2: Result Student t-Test
There is no statistically
significant difference between Control and 100.00 mg/L.
Pair-wise comparison of treatments
with "Control" by the t-test procedure. Significance was Alpha = 0.05,
one-sided smaller; Mean: arithmetic mean of growth rates; n: sample
size; s²: variance; % MDD: minimum detectable difference to Control (in
percent of Control); t: sample t; p(t): probability of sample t for Ho:
µ1 = µ2; the differences are significant in case p(i) <= Alpha; p(F):
probability of F computed by a F-test (Ho: var1 = var2 (homogeneity);
p(F) > 0.05 is the criterion of variance homogeneity.
(The residual variance of an ANOVA was
applied; df = N - k; N: sum of treatment replicates n(i); k: number of
of accompanying chemical analysis
results of the elemental analysis of zirconium and ytterbium demonstrate
that the solubility of both is below the limit of quantification (< 1
µg/L) in the test medium. In the test solution with a nominal loading
rate of 100 mg/L no detection of zirconium and ytterbium could be
measured. Measurements of all samples of zirconium and ytterbium were
below the limit of quantification (< 1 µg/L). No detection of dissolved
Zirconium and Ytterbium could be measured in 100 mg/L of the test
samples. The reference standard sample of Ytterbium of 1 mg/L was
detected with 0.830 mg/L and within the accepted range of +/- 20 %. The
reference standard samples of zirconium of 1 mg/L was detect with 0.720
mg/L. For a second measurement the reference standard and the samples of
0h of the control and 100 mg/L were measured. The standard was detected
with 0.880 mg/L and was within the accepted range. The sample
measurement was again below the LOQ.
Figure 1 (see below) shows the mean cell
concentration of the test culture and the controls plotted against time
of exposure in a logarithmic scale (growth curves). Algal growth is
exponentially in both control and test treatment. The growth in the test
treatment is similar compared to the control. In Appendix II, the
determination of the conversion factor between cell count and measured
chlorophyll fluorescence is presented.
of validity for this study (after 72 h of exposure)
The biomass in the controls increased within 72 h from 0.07 x 105 algal
cells/mL to 5.77 x 105 (factor 88) which is within the range for
validity for the test (required ≥ 16).
The maximum mean variation coefficient of the growth rate from day to
day (day 0-1, 1-2 and 2-3) was 31.5 % in the controls which is within
the validity range of 0 – 35 %.
The variation coefficient calculated for the mean growth rate from day 0
to day 3 was 1.7 % and below the upper limit of 7 %.
The test is valid according to OECD 201.
a 72 hour acute toxicity study (algae growth inhibition test), the
cultures of Raphidocelis subcapitata (Strain No. 61.81 SAG) were
exposed to the test item
at nominal concentrations of 0.0 (control) and 100 mg/L under
static conditions in accordance with the OECD
The NOErLR value was ≥ 100 mg/L, the ErLR50 was > 100 mg/L based on cell
density respectively. The nominal effective loading rate resulted in no
inhibition of the growth rate.
were no compound related phytotoxic effects.
Accompanying chemical analysis revealed that
the solubility of elemental zirconium and ytterbium released from the test
item is below the limit of quantification (< 1 μg/L).
toxicity study is classified as acceptable and satisfies the guideline
requirements for an algae growth inhibition toxicity study.
Organism: Raphidocelis subcapitata (Strain No. 61.81 SAG)
Test type: Static
- 72 h NOErLR: ≥ 100 mg/L (nominal loading)
- 72 h ErLR50 : > 100 mg/L (nominal loading)
Endpoint Effected: Growth rate
NOErLR to cultures of Raphidocelis subcapitata determined
according OECD guideline 201 is ≥ 100 mg/L (nominal).
Accompanying chemical analysis revealed that
the solubility of elemental zirconium and ytterbium released from the
test item is below the limit of quantification (< 1 μg/L).
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