2H-Tetrazol-5-amine, potassium salt (1:1)

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:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

The temperature in the positive control and in the main study was higher than stated in the guidelines. The last photometric measurement was after 70.5 hours instead of 72 hours. Both deviation were stated as uncritical.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

potassium 5-amino-1H-1,2,3,4-tetrazol-1-ide

Cas Number:

136369-04-5

Molecular formula:

CH2KN5

IUPAC Name:

potassium 5-amino-1H-1,2,3,4-tetrazol-1-ide

Test material form:

solid: particulate/powder

Details on test material:

Batch no.: 08KI030

Sampling and analysis

Analytical monitoring:

yes

Remarks:

The concentrations of 5-Aminotetrazol Potassium were determined using a validated HPLC method.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Unicellular freshwater green alga.
Genus, Species: Desmodesmus subspicatus
Strain: CHODAT
Family: Chlorophyceae
Order: Chlorococcales
The culture of Desmodesmus subspicatus was obtained in Feb. 2008 by the "Collection of Alga“, Institut für Pflanzenphysiologie of Universität Göttingen. The alga are kept as stock culture on solid agar at 8 °C. From an aliquot of this stock culture, the pre-culture was prepared.

Study design

Total exposure duration:

72 h

Test conditions

Test temperature:

26°C to 31°C

pH:

7.3 to 8.0

Nominal and measured concentrations:

Nominal: 0, 4.6, 10, 22, 46, 100, 220 and 460 mg/L
The measured concentrations showed very good correlation with the nominal concentrations. The recovery rate after 72 hours were between 99 and 101 %. The measured concentrations lay in a range of 100 % - 102 % of the nominal concentration. Therefore the nominal concentrations were used for the determination of the biological results.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (CAS# 7778-50-9)

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 460 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

4.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

The EC50s of potassium dichromate were determined in a current reference study. For the estimation of the EC50s of the positive control, the fits showed good statistical correspondence of the data with the dose-response-equation. The values were within the normal range of the laboratory as well as in correspondence with the values from the international ring test which are stated in EU Method C.3.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

For the estimation of the EC50s of the test item, the fits showed sufficient statistical correspondence of the data with the dose-response-equation. The analytical determinations of the test item showed very good correlation between nominal and measured concentrations and very good recovery rates. Therefore the test item 5-Aminotetrazol Potassium can be stated as stable under the test conditions and the determination of the results was based on the nominal concentrations. The result of the test can be considered valid.

Executive summary:

Three experiments were performed. As the first and the second experiment were not valid, a third experiment was performed. The study was performed using seven concentrations ranging from 4.6 to 460 mg/L. The treatments were used to incubate the unicellular freshwater green alga Desmodesmus subspicatus for a period of 72 hours. The cell concentration of each replicate was determined by measuring the absorption of the cuvettes at 440 nm every 24 hours with a spectral photometer. With these measured values, the number of cells was calculated (linear correlation between cell concentration and absorption given). Then the growth rate μ, the area under the growth curve (AUC1) and the Yield2 were determined. At the start and at the end of the test, the content of test item in the test solutions was determined using HPLC. The recovery after 72 hours ranged from 99 % to 101 % of the start concentration. The correlation between nominal and measured concentration was 100% - 101 % at the beginning and 100 – 102 % at the end. Therefore, the determination of the results was based on the nominal concentrations. The EC50s of potassium dichromate were determined in a current reference test. The values lay within the normal range of the laboratory. The following results for the test item 5-Aminotetrazol Potassium were determined:

Endpoint	NOEC	LOEC	EC50
Growth rate µ	4.6 mg/L	10 mg/L	> 460 mg/L
Biointegral AUC	10 mg/L	22 mg/L	42 mg/L
Yield	4.6 mg/L	10 mg/L	11 mg/L