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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28.05.2018-17.09.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Specification: Unicellular freshwater green alga.
Genus Desmodesmus
Species subspicatus
SAG Strain Number 86.81
Taxonomic position Chlorophyta - Chlorophyceae
Origin and Culture:
The culture of Desmodesmus subspicatus was obtained in February 2014 by MBM Sci-encebridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen). The algae are kept as stock culture on solid agar at 2 - 8 °C. From the stock culture, a permanent culture was prepared. From an aliquot of the permanent culture, the pre-culture was prepared.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Test conditions

Nominal and measured concentrations:
0.1 / 0.32 / 1 / 3.2 / 10 / 32 / 100 mg/L (nominal)
0.06 / 0.18 / 0.55 / 1.76 / 5.5 / 17.6 / 55 mg/L (active ingredient)
Reference substance (positive control):
yes
Remarks:
Potassium dichromate K2Cr2O7

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
2.96 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.:
< 1.63 µg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: large difference between EC50 and NOEC due to strong growth in control
Details on results:
The result should be considered with care, as the growth factor in the control was well above the required value of 16fold. In this experiment a factor of 185 was determined. This leads to a decrease in the lowest concentration by 24%. However, the further reduction with increasing concentration is low (shallow concentration-response curve). A 50% reduction in growth rate was not reached at the highest test concentration.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The toxicity to aquatic algae was determined and the NOEC and EC50 for growth rate after 72 hours was <16 µg/L and 2.96 mg/L, respectively.
Executive summary:

The toxicity of of the test substance to Desmodesmus subspicatus was investigated in a study conducted according to OECD Guideline 201 (Alga, Growth Inhibition Test; 2006/2011) and EU Method C.3 (Algal Inhibition Test; 2008/2009). The 72 h NOEC and EC50 values based on growth rate were determined to be <16 µg/L and 3 mg/L, respectively. However, there is a strong growth in contraol taht may have an impact on the results. Therefore, the values should be used with care.