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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
03.-07.12.18
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
2006
Deviations:
yes
Remarks:
uncritical: stock solutions were autoclaved for 20 minutes, pre-culture was prepared 5 days before test start (validity criteria were observed)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: granular

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name:
- Strain: 86.81
- Source (laboratory, culture collection): MBM Sciencebridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen), Jan 2006
- Age of inoculum (at test initiation):
- Method of cultivation:

ACCLIMATION
- Acclimation period:
- Culturing media and conditions (same as test or not):
- Any deformed or abnormal cells observed:

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Test conditions

Test temperature:
21.7 – 22.8 °C
pH:
7.6-8.3
Nominal and measured concentrations:
nominal concentration: 1 / 3.2 / 10 / 32 / 100 mg/L
geometric mean: 0.02 / 0.06 / 0.19 / 0.67 / 1.85 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: glass flasks
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 45 ±1 mL
- Aeration:
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate):
- Initial cells density: 2.4E3
- Control end cells density: 4.2E5
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): -

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
- Total organic carbon:
- Particulate matter:
- Metals:
- Pesticides:
- Chlorine:
- Alkalinity:
- Ca/mg ratio:
- Conductivity:
- Culture medium different from test medium:
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Adjustment of pH:
- Photoperiod:
- Light intensity and quality: 5000 lux
- Salinity (for marine algae):

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]
- Chlorophyll measurement:
- Other:

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:
Reference substance (positive control):
yes
Remarks:
K2Cr2O7 (CAS No. 7778-50-9)

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.02 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.06 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.95 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 1.95 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
72h EC50 0.79 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Executive summary:

The study was performed using 5 concentrations ranging from 1 to 100 mg/L (nominal). Incubation time (test system Desmodesmus subspicatus)was 72 hours. The cell concentration of each replicate was determined by measuring the cell numbers every 24 hours with an electronic particle counter. Growth rate µ and the yield were determined from the cell number at the respective observation times.

Significant inhibition of algal growth was observed at the following concentrations:

3.2 – 100 mg/L (nominal concentrations)

 

At the beginning and at the end of the test, the content of the test item in the test solutions was determined using HPLC-UV-determination. Because of the poor solubility of the test item the measured concentrations lay between 1 % and 4 % of the nominal concentration during the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations.

 

The 72h-EC50values of potassium dichromate (K2Cr2O7, CAS No. 7778-50-9) were determined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.73 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).

 

The following results for the test item 1,1'-Azobis(cyclohexane-1-carbonitrile) were determined:

Table 3‑a         Results of the test item

Endpoint

NOEC

LOEC

EC10

EC50

Growth Rate

0.02 mg/L

0.06 mg/L

0.95 mg/L

> 1.85 mg/L

Yield

0.02 mg/L

0.06 mg/L

0.34 mg/L

0.94 mg/L