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Ecotoxicological information

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
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution of 20 mg test item/L was prepared by dissolving 20.7 mg test item into 1035 mL test water by intense stirring for 15 minutes. 10 mL of this concentrated stock solution was further diluted with 90 mL test water to prepare a second diluted stock solution of 2 mg/L. Adequate volumes of this diluted stock solution were added to defined volumes of test water to prepare the test media of the desired test concentrations. The tested concentrations were below the limit of quantification.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: No. 61.81 SAG
- Source (laboratory, culture collection): cultivated in the laboratories of IBACON; original source: "Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen", 37073 Göttingen, Germany

ACCLIMATION
- Acclimation period:
- Culturing media and conditions (same as test or not):
- Any deformed or abnormal cells observed:
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
22 to 23 °C
pH:
- at test start 7.8 to 8.0
- at the end of the test 8.2 to 9.4
Nominal and measured concentrations:
Nominal test concentrations: control, 0.8, 2.5, 8.0, 25, and 80 μg test item/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks covered with glass dishes
- Size, fill volume: 50 mL, 50 mL
- Initial cells density: 5000 algal cells per mL test medium; 0.69 mL algae suspension into 150 mL test medium
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

OTHER TEST CONDITIONS
- Photoperiod: continuous
- Light intensity and quality: 6760 lux (5790 to 8070 lux)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: The cell densities in the samples were determined by spectrophotometrical measurement

TEST CONCENTRATIONS
- Range finding study: yes, non-GLP
- Test concentrations: 0.05, 0.5, 5 and 50 mg test item/L
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
29.8 µg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
58.7 µg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- In the freshly prepared stock solution 9 mg Carbon/L could be detected.
- After 72 h the content of Carbon was 9 mg/L.
Results with reference substance (positive control):
- The reference item potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.
Validity criteria fulfilled:
yes
Conclusions:
The test substance showed to be acutely very toxic and toxic based on long-term expsoure for freshwater algae.

Description of key information

EC50(72h) = 0.058 mg/L (nominal) for growth rate of Pseudokirchneriella subcapitata (OECD 201)

EC10(72h) = 0.029 mg/L (nominal) for growth rate of Pseudokirchneriella subcapitata (OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:
0.058 mg/L
EC10 or NOEC for freshwater algae:
0.029 mg/L

Additional information

The toxicity on aquatic algae was investigated for the Sulfonium compond mixture in a GLP guideline study according to the OECD 201 (BASF 2013). The study was conducted with the green algae species Pseudokirchnerella subcapitata. After 72 hours of exposure the ErC50 was 0.058 mg/L and the ErC10 was 0.029 mg/L (nominal).