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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study according to OECD Guideline No. 201 and EC Directive 92/69/EC Method C.3
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
GLP according to OECD, EC and German principles of GLP
Analytical monitoring:
no
Details on sampling:
.
Vehicle:
no
Details on test solutions:
PREPARATION OF TEST SOLUTION
Preparation of the saturated solution one day prior to application: A dispersion (100 mg/L test item was weighed out) was prepared with dilution water, shaken with 20 rpm for 24 h and membrane filtrated with 0.45µm (RC55, S&S 10410214).
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: Desmodesmus subspicatus CHODAT SAG 86.81
- Source (laboratory, culture collection): Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches Institut der Universität Göttingen, Göttingen, Germany
- Age of inoculum (at test initiation): four day-old preculture
- Method of cultivation: Fresh stocks were prepared every month on Z-Agar. Light intensity amounted 35-70 μE·m-2·s-1 for 24 h per day.

ACCLIMATION
- Acclimation period: four days, see above
- Culturing media and conditions (same as test or not): preculture incubated in 500 mL Erlenmeyer flasks; all algae were from the same source.
- Any deformed or abnormal cells observed: no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
None. Observations were carried out during exposure at the beginning of the experiment and after 24, 48 and 72 hours.
Hardness:
0.22 mmol Ca+Mg/l for the dilution water
Test temperature:
22-23 (mean: 22.5) °C
pH:
Start: 8.27 (test solution), 8.26 (control)
End, 72 h: 8.43 (test solution), 8.42 (control)
Nominal and measured concentrations:
A limit test with a saturated solution of nominally 100 mg/L (see above) was carried out.
Details on test conditions:
TEST SYSTEM
- Test vessel: Sterile erlenmeyer flasks, volume: 250 mL
- Test volume: 100 mL
- Initial cells density: appr. 10000 cells/mL
- Control end cells density: 1196245 (mean from 6 replicates) cells/mL
- No. of vessels per limit concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dilution water according to guidelines
- Intervals of water quality measurement: at the start and at the end (72 h)

OTHER TEST CONDITIONS
- Sterile test conditions: yes (sterile erlenmeyer flasks were used)
- Photoperiod: 24 h/d light
- Light intensity and quality: min. 64.0, max. 73.9 (mean 69.5 μE·m-2·s-1)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Chlorophyll-impulsfluorometer
- Chlorophyll measurement: Chlorophyll-a-fluorescence, excitation at 435 nm, emission at 685 nm
- Other: measurements at the beginning of the test (after application) and every 24 h, filtrated culture medium was used as ground signal. Each replicate was measured 6-fold.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: only one concentration (saturated solution), limit test
- Justification for using less concentrations than requested by guideline: limit test
Reference substance (positive control):
yes
Remarks:
Potassium dichromate p.a.
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Basis for effect:
growth rate
Remarks on result:
other: not applicable
Key result
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Basis for effect:
growth rate
Remarks on result:
other: not applicable
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Basis for effect:
growth rate
Remarks on result:
other: not applicable
Details on results:
NOEC, LOEC and EC50 values for Inhibition of biomass growth and rate-related inhibition.

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no

Environmental conditions, pH-value, measured at 0 and 72 h, and room temperature, measured continuously, met the validity criteria of the guideline.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50 (biomass growth): 0.29 mg/l (0-72 h), 95 % confidence interval: 0.26-0.33 mg/l
- EC50 (rate-related inhibition): 0.59 mg/l (0-72 h), 95 % confidence interval: 0.55-0.63 mg/l
Reported statistics and error estimates:
The NOEC and LOEC were determined by calculation of statistical significance of biomass integrals and growth rates. One Way Analysis of Variance (ANOVA) and DUNNETT’s test was carried out for the determination of statistically significant differences compared to control replicates. When running a One Way Analysis of Variance a Normality Test and an Equal Variance Test were done first. P-values for both Normality and Equal Variance Tests were 0.05. The α-value for ANOVA was α=0.05.
Validity criteria fulfilled:
yes
Conclusions:
No inhibiting effects on biomass growth and specific growth rate were found in the saturated solution. The EC50-values for inhibition of biomass growth (EbC50) and specific growth rate (ErC50) after 72 h were > 100 mg/L (nominal).
Executive summary:

The toxicity of Hostaperm-Violett RL spez. (Batch no.: DEBF 062509) to the unicellular freshwater green alga Desmodesmus subspicatus was determined according to the principles of OECD-Guideline 201 (1984) and EC Directive 92/69/EC Method C.3 at DR.U.NOACK-LABORATORIEN in 31157 Sarstedt, Germany from May 22 to 25, 2006. The aim of the study was to assess the effects on growth rate and biomass production over a period of 72 h. The study was conducted under static conditions with an initial cell density of appr. 10000 cells/mL. A limit test with a saturated solution was carried out. A dispersion of 100 mg/L was prepared in dilution water, shaken with 20 rpm shaken with 20 rpm for 24 h and membrane filtrated with 0.45µm. Three replicates were tested for the saturated solution and 6 replicates for the control. Environmental conditions, pH-value and room temperature, were determined to be within the acceptable limits. All effect values are based on the saturated solution of the test item.

In this study Hostaperm-Violett RL spez. did not cause any inhibiting effects to Desmodesmus subspicatus after 72 h when tested with a saturated solution.

Description of key information

In this OECD 201 study the test item (Pigment Violet 23) did not cause any inhibiting effects to Desmodesmus subspicatus after 72 h when tested with a saturated solution.

Key value for chemical safety assessment

Additional information

The toxicity of teh test item to the unicellular freshwater green alga Desmodesmus subspicatus was determined according to the principles of OECD-Guideline 201. A limit test with a saturated solution was carried out.

In this study teh test item did not cause any inhibiting effects to Desmodesmus subspicatus after 72 h when tested with a saturated solution.

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