Registration Dossier

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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well documented study according to international accepted guideline and GLP compliant.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report Date:
2016

Materials and methods

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

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
Test item: 4-Aminobutyric acid
CAS number: 56-12-2
Batch number BCBN4740V
Physical state: Solid, crystalline powder
Colour: White
Storage: at 15-30 °C

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
yes
Details on test solutions:
PREPARATION OF STOCK SOLUTION
The preparation of stock and test solutions was based on the preliminary non GLP range finding test. For the stock solution 400.08 mg of test item was measured into 2 000 ml OECD medium. The emulsion were stirred and ultrasonicated till complete dilution of test item. The stock solution was clear and colourless. The nominal concentration of stock solutions was 200 mg/L.

PREPARATION OF TEST SOLUTION
Seven test solutions of different concentration were prepared by mixing appropriate volume of OECD medium and stock solution of the test item. These concentrations were arranged in a geometric series with a maximum separation factor 2.0. Three additional replicates were prepared for controlling the abiotic degradation of the test substance. These test vessels were not inoculated with alga inoculum culture.
The volume of the prepared dilution levels was 300 ml except the control solution which was 600 ml.
The alga inoculum culture was diluted 162.16 times so the initial alga cell concentration in every dilution and the control levels were 4 882 cells/ml.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Test species: Pseudokirchneriellasubcapitata (Korshikov)
F.Hindák (formerly known as Selenastrumcapricornutum)
Source: UTEX The Culture Collcetion of Algae (USA)

Study design

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

Test conditions

Test temperature:
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.
pH:
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 nominal concentration of the stock solution was 200 mg/L. In the test the following nominal concentrations were applied: 200; 160; 120; 100; 80; 60 and 40 mg/L.
Details on test conditions:
The test organism was grown and hold in OECD medium which was used also for preparing test itemsolutions.
The toxic property of test item was investigated at seven concentrations which were prepared by different dilutions of stock solution of test item. OECD medium was used for preparation and dilution of stock solution.

At each concentration level three replicates were used. In the case of control six replicates were applied. The initial alga concentration was 4 882 cells/ml. The
vessels were closed with silicone stoppers with a filter for ensuring the proper air exchange. The vessels were kept in incubator at 21 ± 2 °C with continuous
illumination. The treatments of control and test vessels were identical. Three additional replicates were prepared for controlling the abiotic degradation of the test substance. These test vessels were not inoculated with alga inoculum culture. One of the abiotic controls was taken into the incubator with a complete
aluminium foil cover to check the stability of test item in the absence of light. The treatment of other abiotic controls was equal with the test vessels. The number of alga cells was determined daily by microscopically counting with Bürker chamber.

Results and discussion

Effect concentrationsopen allclose all
Dose descriptor:
NOEC
Effect conc.:
>= 200 mg/L
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: 95 % CL
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % CL
Details on results:
The inhibition feature of test item was determined as the EC50 values which was calculated from the average specific growth rates and yield.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
According to this Alga Growth Inhibition Test for 4-Aminobutyric acid the results indicated that the test item is not hazardous to the aquatic environment [72 hr EC50 (for algae or other aquatic plants) > 100 mg/L].