Prop-2-yn-1-yl 1H-imidazole-1-carboxylate

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

Study period:

20 Oct. 2021-27 Jan. 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

adopted 23. Mar. 2006, Annex 5 corrected: 28 July 2011

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: Commission Regulation (EU) No. 2016/266 amending Regulation (EC) No. 440/2008, Annex IV, Method C.3: “FRESHWATER ALGAE AND CYANOBACTERIA, GROWTH INHIBITION TEST."

Version / remarks:

adopted 07. December 2015

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

prop-2-yn-1-yl 1H-imidazole-1-carboxylate

EC Number:

695-595-2

Cas Number:

83395-38-4

Molecular formula:

C7H6N2O2

IUPAC Name:

prop-2-yn-1-yl 1H-imidazole-1-carboxylate

Test material form:

solid

Specific details on test material used for the study:

Name: 2-propyn-1-yl 1H-imidazole-1-carboxylate
Batch no.: 0802-2#
CAS no.: 83395-38-4
Storage: fridge (2 - 8 °C) under inert gas
Expiry date: 21. Mar. 2022
Appearance: white solid
Purity: 99.1 %
Homogeneity: homogeneous
Production date: 13. Oct. 2020
EC no.: 695-595-2
Molecular formula: C7H6N2O2
Molecular weight: 150.13 g/mol

Sampling and analysis

Analytical monitoring:

not specified

Details on sampling:

- Concentrations: 4.6 / 10 / 22 / 46 / 100 mg/L nominal concentration
- Sample storage conditions before analysis: stored in a closed vessel at room temperature (20 ± 5 °C)

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Positive Control: Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9)
- Blank Control: 350 mL nutrient medium
- Stock solution containing 100 mg/L test item in algal medium (demineralised water en-riched with minerals but without algae) was prepared. Lower test concentrations were prepared by dilution of the stock solution in algal medium.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- SAG Strain Number: 86.81
- Taxonomic position: Chlorophyta - Chlorophyceae
- Origin and Culture: The culture of Desmodesmus subspicatus was obtained in May 2020 by MBM Sciencebridge GmbH. The algae are kept as stock cul-ture on solid agar at 2 - 8 °C. From the stock culture, a permanent culture was prepared. From an aliquot of the permanent culture, the pre-culture was prepared.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

21.6-22.5 °C

pH:

7.5-7.6

Nominal and measured concentrations:

Nominal concentration: 4.6/ 10 / 22 / 46 / 100 mg/L
Measured concentration: 6.19 / 13.20 / 28.64 / 60.59 and 136.72 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks total volume 65 mL
- Initial cells number: 2880 Cell Number/mL
- Control end cells number: 320030 Cell Number/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: demineralised water

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Light intensity and quality: within the specified range (4440 – 8880 Lux)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter
- observation intervals: every 24 ± 1 hours

Reference substance (positive control):

yes

Remarks:

Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9)

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

11.85 mg/L

95% CI:

7.58 - 20.13

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.92 mg/L

95% CI:

0.75 - 1.17

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.32 mg/L

95% CI:

0.14 - 0.45

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.34 mg/L

95% CI:

0.09 - 0.75

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 5

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

<= 0.56 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Effect concentrations 6

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

<= 0.56 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 7

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.56 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Effect concentrations 8

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.56 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study, the 72 hour ErC50 of the test material was determined to be 11.85 mg/L.

Executive summary:

In this guideline (OECD 201) study conducted with GLP certification, the objective of this study was to evaluate the toxicity of 2-propyn-1-yl 1H-imidazole-1-carboxylate towards Desmodesmus subspicatus.

The study was performed using 5 concentrations ranging from 4.6 to 100 mg/L (nominal). Incubation time (test system Desmodesmus subspicatus) was 72 hours. The cell concentration of each replicate was determined by measuring the cell numbers every 24 ± 1 hours with an electronic particle counter. Growth rate µ and the yield were determined from the cell number at the respective observation times.

Significant inhibition of algal growth was observed at all concentrations.

 

At the start, after 24 h and after 48 h the content of the test item in the test solutions was determined using HPLC determination. At the beginning of the test, the measured concentrations lay between 130 % and 137 % of the nominal concentrations. Because the test item was not stable under test conditions, after 24h the test item was still detectable only in the two highest concentrations 46 mg/L sand 100 mg/L. Because after 48 h no test item was detectable, no further measurement after 72 h was performed. Therefore, the determination of the results was based on the geometric mean of the measured concentrations. Geometric mean is calculated by multiplication of the n participating concentrations and taking the nth root.

For the three lowest concentrations 4.6 mg/L, 10 mg/L and 22 mg/L, the measured concentration at the beginning, the half of the LOQ (0.05 mg/L) was used for calculation of the geometric mean.

 

The 72h-EC₅₀ values of potassium dichromate (K₂Cr₂O₇, CAS No. 7778-50-9) were determined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.64 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).

 

The following results for the test item 2-propyn-1-yl 1H-imidazole-1-carboxylate were determined:

Table: Results of the test item

Endpoint	NOEC	LOEC	EC10	EC50
Growth Rate	< 0.56 mg/L	≤ 0.56 mg/L	0.34 mg/L (extrapolated)	11.85 mg/L
Yield	< 0.56 mg/L	≤ 0.56 mg/L	0.32 mg/L (extrapolated)	0.92 mg/L