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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
Study period:
2012
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)
Remarks:
EL
Analytical monitoring:
yes
Details on sampling:
- Sampling method: algae separated by centrifugation before analysis
Vehicle:
no
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: G. Brinkmann 1953/SAG86,81
- Source: Institute of Botany, Slovak Academy of Sciences, Bratislava, Slovak Republic
- Method of cultivation: inoculum culture prepared 3 days before test start. Conditions same as under test.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
22 - 24 °C
pH:
7.98 - 8.16
Nominal and measured concentrations:
Initial concentrations: 64, 128, 256, 512, 1024, 2048, 3000 mg/L (nominal)
Measured concentrations at start and end of the test: between -0.27% and +9.91% of nominal
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 mL volume in 150 mL flasks
- Type: closed with air-permeable stoppers
- Materia: glass or other chemically inert material
- Initial cells density: 4160 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, according to OECD

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Sörensen buffer
- Intervals of water quality measurement: pH measured at beginning and end of test

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: stock solution adjusted with 1 N NaOH to pH 8.04
- Photoperiod: continuous illumination
- Light intensity and quality: 8470 - 8590 lux, cool white light, effective wavelength 400 - 700 nm
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
145 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CI: 115-181 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
3 285 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CI: 2619-4119 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
452 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% CI: 247-825 mg/L
Results with reference substance (positive control):
- 72 h-ECr10: 0.32 mg/L (mean of 3 determinations)
- 72 h-ECr50: 0.81 mg/L (mean of 3 determinations)
Reported statistics and error estimates:
y

Growth data:

Nominal concentration
[mg/L]

Inhibition of growth rate
[%]

Inhibition of biomass
[%]

64

1.00

4.4

128

6.71

21.2

256

18.11

42.3

512

25.66

60.8

1024

34.24

72.3

2048

43.65

76.9

3000

50.03

83.9

 

Validity criteria fulfilled:
yes
Executive summary:

A growth inhibition test of TC to the algae Desmodesmus subspicatus was performed according to OECD 201. After 72 h of exposure, the ECr10 was determined to be 145 mg/L and the ECr50 to be 3285 mg/L.

Description of key information

A 72 h growth inhibition test of TC to the algae Desmodesmus subspicatus was performed according to OECD 201.

Key value for chemical safety assessment

EC50 for freshwater algae:
3 285 mg/L
EC10 or NOEC for freshwater algae:
145 mg/L

Additional information

The EC50 (effect: growth rate) was determined to be 3285 mg/L.

The EC50 (effect: biomass) was determined to be 452 mg/L.