Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

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

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
Molecular formula:

Sampling and analysis

Analytical monitoring:

Test solutions

Details on test solutions:
The test organism was grown and hold in OECD medium which was used also for preparing test item solutions. The stock solution was prepared by measuring 70.05 mg of test item into 1 000 ml OECD growth medium. The suspension was ultrasonicated for 15 minutes and then stirred till complete dilution. As the correction factor of the test item is 1.328, the nominal concentration of the stock solution was 52.75 mg/L. The measured concentration of the stock solution was 53.45 mg/L.

Test organisms

Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
Test species: Pseudokirchneriella subcapitata (Korshikov) F.Hindák (formerly known as Selenastrum capricornutum and Raphidocelis subcapitata)
Source: Culture Collection of Algae and Protozoa, Scottish Marine Institute (
Batch: CCAP 278/4
Date of arriving: 27 October 2017

Study design

Test type:
Water media type:
Limit test:
Total exposure duration:
72 h

Test conditions

Test temperature:
The temperature during the test remained in the 21 ± 2 °C range.The temperature inside the incubator at the test vessels was measured and registered continuously by Extech SD200 thermometer and datalogger. Throughout the test the temperature was nearly constant.
At the beginning of the test the pH values were measured in the remaining test solution of the concurrent test vessels at each dilution level.
At the end of the test the pH values were measured in each test vessel. The pH of test solutions was not adjusted at the beginning of the test.
Nominal and measured concentrations:
The toxic property of test item was investigated at five concentrations which were prepared by different dilutions of stock solution of test item. OECD medium was used for dilution of stock solution. In the test the following calculated concentrations were applied: 4.45; 8.91; 14.25; 26.73 and 53.45 mg/L.
Details on test conditions:
Preparation and breeding of inoculum culture
The inoculum culture (IN20/26) was prepared four days before starting the test and it was bred in incubator at 21 ± 2 °C. At the end of incubation, the cell density of the inoculum culture was determined with a Bürker chamber. The cell concentration was 2 541 667 cell/ml
Reference substance (positive control):

Results and discussion

Effect concentrationsopen allclose all
72 h
Dose descriptor:
Effect conc.:
1.3 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
growth rate
72 h
Dose descriptor:
Effect conc.:
2.15 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
72 h
Dose descriptor:
Effect conc.:
5.59 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
The yield is a response variable of the biomass increase during the test which is calculated as the difference of the biomass at the start and at the end of the test. The effective concentrations for yield are signed as EyCx. The EyCx values were determined including the 95 % confidence interval with Probit analysis using linear max. Likelihood regression. The EyC10, EyC20 and EyC50 were calculated for at both 24, 48 and 72 h period.

Applicant's summary and conclusion

Validity criteria fulfilled:
Acute toxic effect of Silyl-fluconazole was investigated in Freshwater Alga and Cyanobacteria, Growth Inhibition Test (according to OECD 201 guideline).
The ErC50 was 5.59 mg/L at 72 h. According to the Council Regulation (EC) 440/2008 Silyl-fluconazole is hazardous to the aquatic environment and classified into the second acute toxic hazardous category [72 h ErC50 (for algae or other aquatic plants) > 1 mg/L but < 10 mg/L]