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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:
2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
23March 2006, Annex 5 corrected: 28 July 2011
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: A separate set of test solutions with three replicates was prepared for analytical determinations of test substance WAF loading.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Water Accommodated Fractions (WAFs) were prepared by weighing portions of the test substance on small plastics trays and subsequently transferred from the trays to 1 liter of distilled water.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: G.Brinkmann 1953/SAG86, 81
- Source: Institut of Botany, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51, Bratislava 45, Slovak Republic
- Age of inoculum (at test initiation): prepared 3 days before start of the test

ACCLIMATION
- Culturing media and conditions (same as test or not): yes
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Test temperature:
21 - 24°C
pH:
8.09 - 8.55 (definitive test)
Nominal and measured concentrations:
Analysis of the WAF loading of the test substance at the start and end of the limit test (100 mg/L WAF loading of the test substance) was sufficient because of the exposure WAF loading varied less than 20% from nominal values during the test (+7.86 %).
Details on test conditions:
TEST SYSTEM
- Test vessel: 150 mL
- Type: closed
- Fill volume: 50 mL
- Initial cells density: 4784 cells/mL (limit test); 4975 cells/mL (definitive test)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Light intensity and quality: uniform fluorescent illumination of «cool-white» type. 5180 - 5210 lux

EFFECT PARAMETERS MEASURED:
Cell growth and yield determined daily, microscopic observation at end of the test

TEST CONCENTRATIONS
- Range finding study: Limit Test indicated that test ErC50 and EyC50 of the test substance WAF loading in the test medium is lower than 100 mg/L.
- Test concentrations: 10 mg/L, 20 mg/L, 40 mg/L, 80 mg/L, 100 mg/L (WAF)
Reference substance (positive control):
yes
Remarks:
Potassium dichromate, K2Cr2O7, Batch NoMPS-ETS-04/2011
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
29.59 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
growth rate
Remarks on result:
other: WAF loading
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
65.6 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
growth rate
Remarks on result:
other: WAF loading
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
18.44 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
biomass
Remarks on result:
other: WAF loading
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
45.54 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
biomass
Remarks on result:
other: WAF loading
Results with reference substance (positive control):
- Results with reference substance valid? yes
- ErC50: 0.74 mg/L
- ErC10: 0.29 mg/L

Results of the main test (mean of 3 replicates)

Concentration [mg/L]

Growth rate Inhibition [%]

Yield Inhibition [%]

10

0.53

4.4

20

1.93

13.5

40

4.14

24.4

80

14.66

57.1

100

78.98

97.5

 

Validity criteria fulfilled:
yes
Conclusions:
In a growth inhibition test according to OECD 201, an ErC10 of 29.59 mg/L and an ErC50 of 65.6 mg/L (WAF) was determined.
Executive summary:

The toxicity of MC A45A to the alga Desmodesmus subspicatus was determined in a growth inhibition test according to OECD 201. Due to the limited water solubility of the test item, the test was therefore performed on water accommodated fractions (WAF).

Analysis of the test item performed during a limit test revealed that WAF loading varied less than 20% from nominal values.

The results of testing reference substance are consistent with literature data.

Description of key information

The effect values were obtained in a valid test according to OECD 201.

Key value for chemical safety assessment

EC50 for freshwater algae:
65.6 mg/L
EC10 or NOEC for freshwater algae:
29.59 mg/L

Additional information