Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
ANALOGUE APPROACH JUSTIFICATION
Please refer to the attached read across justification in section 13
Reason / purpose for cross-reference:
read-across source
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: area under the growth curve
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: area under the growth curve

Description of key information

The 72 h NOEC (growth rate and biomass) was determined to be 108 mg/L and the EC50 (growth rate and biomass) was determined to be > 108 mg/L. The NOEC and EC50 of the target substance is determined to be > 100 mg/L; this value was derived by taking only the active ingredient into account, as the source substance contains approx. 7 % water (reference 6.1.5-1).

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

No experimental data on the toxicity to aquatic algae with the test item was available. Read-across to a structural analogous substance was done instead.


The effect of the source substance on algal growth was assessed using the unicellular green alga Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata and Selenastrum capricornutum) in a study according to OECD TG 201 under GLP conditions. For this purpose, alga was exposed to the test item for 72 hours. Based on the results of a non-GLP preliminary test, in which the test item had no toxic effect on algae up to the limit concentration of 100 mg/L. Therefore the main test was performed at 108 mg/L including a concurrent control and the reference substance potassium dichromate which served as the reference control. This concentration was chosen for regulatory purposes to achieve the limit test concentration of 100 mg/L for the test item even after a possible correction for the water content. The measured test item concentration remained within ± 20 % of the nominal concentration over the test period of 72 hours. Therefore the biological results were based on the nominal concentration. Exponentially growing cultures of Raphidocelis subcapitata were exposed to the test item over several generations under defined conditions (static test). The algal growth was determined over a fixed test period of 72 hours in relation to a concurrent untreated control culture. Per test concentration and control, six replicates were used. The alga cell concentration was approximately 10e4 cells/mL at the start of the test for all test cultures. Glass flasks with a total capacity of 250 mL were used as test vessels. The volume of the test liquid in the vessels was 100 mL. The alga cell concentration was determined by microscope in each testing flask at 24, 48 and 72 hours. All validity criteria were fulfilled. The 72 h NOEC (growth rate and biomass) of the source test item was determined to be 108 mg/L and the EC50 (growth rate and biomass) was determined to be > 108 mg/L.


Based on the data from the read-across source substance, the target substance's NOEC and EC50 values were determined to be > 100 mg/L; this value was derived by taking only the active ingredient into account, as the source substance contains approx. 7 % water.