Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2011

GLP compliance:

yes (incl. QA statement)

Remarks:

Sächsische Staatsministerium für Umwelt und Landwirtschaft, Germany

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0 and 100 mg/L
- Sampling: at the start and at the end of the test
- Sample storage conditions before analysis: samples were frozen

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution was prepared by weighing 100.0 mg test item and filling up to approx. 990 mL with test medium and mixing well. 6.45 mL algal inoculum (measured 77.5 x 104 cells/mL) were added and test medium was added to a total volume of 1000 mL.
- Eluate: no
- Differential loading: no
- Controls: yes, test medium control

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: freshwater green algae
- Source (laboratory, culture collection): purchased from “Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Experimentelle Phykologie und Sammlung von Algenkulturen” at the University of Göttingen, Germany, in July 2009, strain: 86.81 SAG (further cultivation in the test facility)
- Breeding: glass flasks with 1000 mL growth medium (OECD medium) kept at 24 ± 2°C with continuous illumination of universal white-type fluorescent light (400-700 nm), intensity: approx. 70 μE·m-2·s-1
- Conditions of the algae used in the test: cultures in logarithmic growth phase

ACCLIMATION
Axenic stock cultures grew in culturing vessels for 3 days prior to test initiation; cultivation was performed in glass flasks with the medium described above; algae were kept at the same temperature and light culturing conditions as during the test.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

22.6 - 23.4 °C

pH:

8.11 - 9.4

Nominal and measured concentrations:

Nominal: 0 and 100 mg/L
Recoveries: 91.2% at 0 h and 88.5% at 72 h

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flask
- Type (delete if not applicable): closed with air-permeable stoppers
- Material, size, headspace, fill volume: 250 mL Erlenmeyer flask, 100 mL test volume, headspace: 150 mL
- Initial cells density: 5000 cells/mL in each replicate
- Control end cells density: 1186700 cells/mL (mean)
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: no
- Intervals of water quality measurement: temperature recorded continuously, pH at the start and at the end

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuous illumination
- Light intensity and quality: on average 106 μE m-2 s-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: actual microscopic cell count using a Neubauer counting chamber, at 24, 48 and 72 hours after the start of the test

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Details on results:

- No statistically significant effects (p ≤ 0.05) on growth rate and yield of Desmodesmus subspicatus were observed
- Exponential growth in the control (for algal test): yes

Results with reference substance (positive control):

- The reference item potassium dichromate is routinely tested at concentrations of 0.13, 0.25, 0.5, 1.0 and 2.0 mg a.i./L in a separate study.
- ErC50: 1.01 mg/L
- EyC50: 0.38 mg/L
- NOEC: 0.13 mg/L

Reported statistics and error estimates:

NOEC / LOEC calculation for average specific growth rate after 72 hours (based on nominal test item concentrations) were performed using the STUDENT-t test for Homogeneous Variances.

The mean measured concentrations of the substance in the test solutions remained at 91% of nominal values at the start of the test and at 89% at the end of the test (after 72 h). Therefore the toxicity results are based on the nominal concentrations.

Validity criteria fulfilled:

yes

Description of key information

ErC50 (72 h) > 100 mg/L (Desmodesmus subspicatus; OECD 201)

NOErC (72 h) >= 100 mg/L (Desmodesmus subspicatus; OECD 201)

Additional information

One study is available on the toxicity of Reaction mass of 2-(3,4-dimethyl-1H-pyrazol-1-yl)succinic acid and 2-(4,5-dimethyl-1H-pyrazol-1-yl)succinic acid to algae. The study was conducted as a limit test according to OECD Guideline 201 and GLP (Juckeland, 2012). The test organism Desmodesmus subspicatus was exposed to the test substance at a nominal concentration of 100 mg/L for 72 hours. No statistically significant effect on growth rate and yield was observed during the study. The NOEC is thus determined to be >= 100 mg/L and the EC50 > 100 mg/L.