2-phenylimidazole

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 Nov 2017 - 30 Jan 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

13 April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesanstalt für Umwelt, Messungen und Naturschutz Baden-Württemberg, Karlsruhe, Germany

Test material

Test material information

Constituent 1

Reference substance name:

2-phenylimidazole

EC Number:

211-581-7

EC Name:

2-phenylimidazole

Cas Number:

670-96-2

Molecular formula:

C9H8N2

IUPAC Name:

2-phenyl-1H-imidazole

Test material form:

solid: flakes

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Analytical samples were taken from the highest test item concentration and control at test start and after 24 hours from fresh and aged solutions and after 48 hours from aged solutions. For each sampling also a retain sample was taken.
- Sample storage conditions before analysis: All samples were stored deep frozen until they were transferred to the analytical laboratory.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A saturated stock solution was prepared by directly weighing 100 mg in 1000 mL test medium. This stock solution was stirred in the dark at room temperature for 24 h and let settle down for another hour (based on OECD Series on Testing and Assessment No. 23). After the settling the necessary volumes for the test were withdrawn via a Teflon tube from the medium level of the stock solution. The test item concentrations were made by diluting the appropriate solutions to give the required test concentrations. The preparation procedure was repeated after 24 hours. Around 50 mL of the prepared solutions were transferred to each test vessel.
- Controls: blank control without the test item
- Eluate: no
- Differential loading: no
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): After filtration the test solution was clear and transparent.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Source: Continuously bred in the laboratory and originally purchased in a healthy condition from the Federal Environment Agency in Berlin, Germany.
- Age: Freshly hatched daphnids less than 24 hours old were used for the test.

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test conditions

Hardness:

12°dH (214 mg/L as CaCO3)

Test temperature:

19.1-19.5 °C (mean)

pH:

7.84 - 8.07 (mean)

Dissolved oxygen:

9.1 - 9.2 mg O2/L

Nominal and measured concentrations:

nominal: 100, 45.5, 20.7, 9.39, 4.27 mg/L, and control
measured range: 105-117, 49.0-51.3, 22.8-23.5, 10.2-10.3, 4.25-4.48 mg/L, and < LOD

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass vessel (100 mL), were filled up with ~ 50 mL test solution. The test units were covered with a glass plate.
- Renewal rate of test solution: The test solutions were freshly prepared at 0 and 24 h.
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
Elendt M4 standard medium was used as test medium. At test initiation the pH-value of the control (untreated test medium) was 7.69, the dissolved oxygen concentration was 9.3 mg/L and the total hardness was 12°dH (214 mg/L as CaCO3).
The test temperature and the pH-value as well as the oxygen concentration of the test solutions were measured at all concentrations at t = 0 h fresh and t = 24 h from fresh test solutions and after t = 24 h and t = 48 h from aged test solutions in one separate replicate per test item concentration without test organisms.

OTHER TEST CONDITIONS
- Photoperiod: 16 h light / 8 h dark
- Adjustment of pH: no

EFFECT PARAMETERS MEASURED (with observation intervals if applicable)
- Immobility after 24 and 48 h
- Behavioural changes of daphnids were recorded at 24 and 48 hours after starting the test.

RANGE-FINDING STUDY
A range-finding test was performed to define the test concentrations. However, the results are not reported.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

13 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

4.27 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Mortality of control: 10%
- Behavioural changes: After 24 and 48 hours the mobile daphnids in the highest test item concentration of 100 mg/L were found to be swimming close to the water surface.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No; Test solutions were clear and colorless

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50 (24 h) = 1.00 - 2.00 mg/L

Reported statistics and error estimates:

The 24 h and 48 h EC50 are the estimated concentrations where 50 % of the daphnids were immobilised after 24 and 48 hours, respectively.
The values for EC50 were determined by Probit analysis using linear max likelihood regression. The evaluation of data was performed by ToxRat Professional 3.2.1.
The NOEC was established based on the highest concentration at which the immobilisation is not higher than the allowed control immobilisation ( ± 10 % immobilisation).

Any other information on results incl. tables

Table 1: Determined concentration of the test substance

Test substance	Sampling		Test substance
nominal [mg/L]	[h]		[mg/L]	% of nominal
Control		0 fresh	n.d.	-
		24 aged	n.d.	-
		24 fresh	n.d.	-
		48 aged	n.d.	-
4.27		0 fresh	4.25	100
		24 aged	4.48	105
		24 fresh	4.32	101
		48 aged	4.48	105
9.39		0 fresh	10.2	109
		24 aged	10.3	110
		24 fresh	10.3	110
		48 aged	10.2	109
20.7		0 fresh	22.8	110
		24 aged	23.5	114
		24 fresh	23.2	112
		48 aged	22.8	110
45.5		0 fresh	49.0	108
		24 aged	51.3	113
		24 fresh	49.4	109
		48 aged	51.3	113
100		0 fresh	105	105
		24 aged	117	117
		24 fresh	112	112
		48 aged	109	109

Table 2: Validity criteria

Criterion from the guideline	Outcome	Validity criterion fulfilled
In the control, including the control containing the solubilising agent, not more than 10% of the daphnids should have been immobilized.	10 %	yes
The dissolved oxygen concentration at the end of the test should be ≥ 3 mg/L in control and test vessels.	≥ 8.8 mg/L	yes

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.