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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
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot no.of test material: 20140124
- Expiration date of the lot/batch: 22 May 2019
- Purity test date: 22 May 2017

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Ambient temperature
- Stability under test conditions: No data
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Nominal 4.24, 9.39, 20.7, 45.5 and 100mg/L
- Sampling method: Three replicate samples (duplicate samples for analysis and 1 reserve sample) were taken from freshly prepared test solutions at 0h and from aged 72h pooled samples. Duplicate samples (1 sample for analysis and 1 reserve sample) were taken from test vessels at 24 and 48h.
- Sample storage conditions before analysis: All samples were frozen on day of sampling until required for analysis
Vehicle:
no
Details on test solutions:
Nominal 500mg/L stock solution of test substance prepared in OECD test medium. Test solutions prepared by dilution from 500 mg/L stock solution
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa (CCAP)
- Age of inoculum (at test initiation): 6 days
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
No data
Test temperature:
22+/-2oC
pH:
0h: 4.1-7.9
72h: 7.9-8.0
Dissolved oxygen:
No data
Salinity:
No data
Conductivity:
No data
Nominal and measured concentrations:
Nominal test concentrations (0h): Control, 4.27, 9.39, 20.7, 45.5 and 100 mg/L
Geometric mean measured test concentrations (72h): Control, 0.20, 0.30, 0.45, 0.66 and 4.41 mg/L
Details on test conditions:
TEST SYSTEM
- Material, size, headspace: Glass 250 mL conical flasks with foam bungs
- Fill volume: 100 mL
- Aeration: None but vessels were continuously shaken at 150 rpm (nominal)
- Initial cells density: 1 x 10/4 cells/mL
- Control end cells density:
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): Not applicable

GROWTH MEDIUM
- Standard medium used: Yes

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:
- 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:
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
>= 4.41 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 0.66 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.:
>= 4.41 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.:
>= 2.81 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 0.66 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
>= 4.41 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
- Exponential growth in the control (for algal test): Yes (16x growth)
- Observation of abnormalities (for algal test): No data
- Unusual cell shape: No data
- Colour differences: No data
- Flocculation: No data
- Adherence to test vessels: No data
- Aggregation of algal cells: No data
- Any stimulation of growth found in any treatment: No
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: None
Validity criteria fulfilled:
yes
Conclusions:
The 72 hour ErC50 (growth rate) was determined as >4.41 mg/L and the EyC50 (biomass) was determined to be 2.81 mg/L based on geometric mean measured test concentrations
Executive summary:

In a 72 -hour toxicity study the green alga, Pseudokirchenriella subcapitata, was exposed to a range of test concentrations under static conditions in accordance with the OECD test guideline 201 and in compliance with GLP. The nominal test concentrations were a control and 4.27, 9.39, 20.7, 45.5 and 100 mg/L, with geometric mean measured test concentrations of 0.20, 0.30, 0.45, 0.66 and 4.41 mg/L, respectively.

A statistically significant inhibition in growth rate and yield (biomass) was observed at the geometric mean measured concentration of 4.41 mg/L. The ErC50 was >4.41 mg/L and the EyC50 was 2.81 mg/L.

This toxicity study is considered acceptable and satisfies the guideline requirements for an algal growth inhibition test.

Description of key information

In a reliable 72 -hour toxicity study the green alga, Pseudokirchenriella subcapitata, was exposed to a range of test concentrations under static conditions, in accordance with the OECD test guideline 201 and in compliance with GLP.

A statistically significant inhibition in growth rate and yield (biomass) was observed at the geometric mean measured concentration of 4.41 mg/L. The ErC50 was >4.41 mg/L and the EyC50 was 2.81 mg/L.

This toxicity study is considered acceptable and satisfies the guideline requirements for an algal growth inhibition test.

Key value for chemical safety assessment

EC50 for freshwater algae:
2.81 mg/L

Additional information