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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:
11 September 2017 - 29 November 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
The following nominal test item concentrations were tested (spaced by a factor of 3.2): 100, 31.3, 9.77, 3.05, 0.954 mg/L and control.
The necessary amount of test item for preparing the stock solution S1 was weighed on a weighing scoop and transferred to a volumetric flask.
Test medium was added up to the bench mark and the solution was homogenised by shaking. Afterwards the solution was clear and
transparent. Lower test solutions were prepared by dilution of appropriate solutions with test medium. All stock and test solutions were prepared
with AAP-medium containing algae cells with a target density of 0.5 × 104 cells per mL.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
strain: SAG 61.81
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
22.7 – 23.0 °C
pH:
7.27 to 8.48
Nominal and measured concentrations:
The measured initial concentrations of acetoacetamide ranged from 78% to 85 % of nominal. In the aged samples the measured content was between 90 % and 91 % of nominal.
Details on test conditions:
The mean light intensity was 88.8 μEm-2s-1 at cell culture level.
Six replicates were employed for the control and three for each test item concentration.
The test was performed in 100 mL Erlenmeyer flasks each containing ~ 50 mL test solution. The pH was recorded at test start and test
end. Temperature was measured continuously over the whole test period and recorded daily. Light intensity of the continuous illumination was
measured at test start.
Reference substance (positive control):
yes
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 83.8 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
31.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
27.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Reported statistics and error estimates:
Where possible NOEC and LOEC were determined by using a multiple comparison method.
Validity criteria fulfilled:
yes
Conclusions:
Due to an inhibition of all parameters (growth rate, yield) below 50 % the database was weak for probit analysis, hence the EC10-value for yield was
not determined and the EC10-, EC20- and EC50-value for growth rate and the EC20- and EC50-value for yield were considered to be > 100 mg/L (nominal)
and > 83.8 mg/L (actual).
Executive summary:

A toxicity study to single cell green alga Desmodesmus subspicatus was performed in year 2017 according to OECD Guideline 201 and GLP.

Significant inhibitory effects were determined for growth rate and yield at test item concentrations of 100 mg/L (nominal) and 83.8 mg/L (actual).

The overall LOEC was therefore determined to be 100 mg/L (nominal) and 83.8 mg/L (actual), the corresponding NOEC was set at 31.3 mg/L (nominal) and 27.5 mg/L (actual).

Due to an inhibition of all parameters (growth rate, yield) below 50 % the database was weak for probit analysis, hence the EC10-value for yield was

not determined and the EC10-, EC20- and EC50-value for growth rate and the EC20- and EC50-value for yield were considered to be > 100 mg/L (nominal)

and > 83.8 mg/L (actual).

Description of key information

A toxicity study to single cell green alga Desmodesmus subspicatus was performed in year 2017 according to OECD Guideline 201 and GLP.

Significant inhibitory effects were determined for growth rate and yield at test item concentrations of 100 mg/L (nominal) and 83.8 mg/L (actual).

The overall LOEC was therefore determined to be 100 mg/L (nominal) and 83.8 mg/L (actual), the corresponding NOEC was set at 31.3 mg/L (nominal) and 27.5 mg/L (actual).

Due to an inhibition of all parameters (growth rate, yield) below 50 % the database was weak for probit analysis, hence the EC10-value for yield was

not determined and the EC10-, EC20- and EC50-value for growth rate and the EC20- and EC50-value for yield were considered to be > 100 mg/L (nominal)

and > 83.8 mg/L (actual).

Key value for chemical safety assessment

EC50 for freshwater algae:
83.8 mg/L
EC10 or NOEC for freshwater algae:
27.5 mg/L

Additional information

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