Imidazo[5,1-f][1,2,4]triazin-4(1H)-one, 2-(2-ethoxyphenyl)-5-methyl-7-propyl-

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:

23. - 30. June 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to OECD guideline under GLP

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Principles of method if other than guideline:

Not relevant

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2-(2-Ethoxyphenyl)-5-methyl-7-propylimidazo-[5,1-f][1,2,4]triazin-4(3H)-one

EC Number:

607-089-0

Cas Number:

224789-21-3

Molecular formula:

C17 H20 N4 O2

IUPAC Name:

2-(2-Ethoxyphenyl)-5-methyl-7-propylimidazo-[5,1-f][1,2,4]triazin-4(3H)-one

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

- Name of test material (as cited in study report): Imidazotriazinon
- Analytical purity: 99%
- Lot/batch No.: BXR6KDD
- Expiration date of the lot/batch: 05-Jul-2016
- Stability under test conditions: At least 3 days
- Storage condition of test material: Room temperature

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Results and discussion

Effect concentrations

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

11.35 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 8.8 - 16.2 mg/L

Any other information on results incl. tables

Table¿1¿1: Inhibition of the growth rate [%] of Desmodesmus subspicatus after 72  hours exposure to Imidazotriazinon
Dilution		Concentration	Inhibition [%]
of Imidazotriazinon		of Imidazotriazinon (mg/L) *	of
in the test vessels		in the test vessels	Growth rate
0		0.0 (control)	0.0
1:100		0.093	-1.0
1:50		0.186	0.5
1:25		0.372	0.1
1:10		0.93	2.1
1:5		1.86	21.4
1:1.25		7.44	39.2
	* Calculated from TOC values

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Imidazotriazinon had a concentration-depended inhibitory effect on the growth of Desmodesmus subspicatus. The ErC50 (growth rate) was 11.354 mg/L [95 % confidence limits: 8.838-16.176] on the basis of measured concentrations. The NOEC was 0.93 mg/L, the LOEC was 1.86 mg/L.

Executive summary:

The purpose of this study was to determine the effects of the test compound Imidazotriazinon on the growth of the green algae Desmodesmus subspicatus. The study was conducted in agreement with the test guideline OECD no. 201.

The test substance Imidazotriazinon was incubated in an aqueous solution including nutrients with an algae population of Desmodesmus subspicatus for a test duration of approximately 72  hours in an incubator shaker apparatus.

The nutrient solution was made up of mainly ammonium, phosphates and some trace elements.

For the preparation of the test solutions a suspension with a nominal loading of 100 mg/L Imidazotriazinon was suspended in demineralized water, sonicated for approximately 30 min and constantly stirred for approximately 24 hours. This suspension was filtered through a glass-fiber filter. The filtered solution was used for the preparation of the test solutions. The highest concentration was a 1:1.25 dilution obtained by adding nutrient solution and inoculum, the further concentrations were obtained by dilutions of 1:5, 1:10, 1:25, 1:50 and 1:100 with demineralized water, nutrient solution and inoculum. Additionally, a control solution was prepared with demineralized water without test material.

The organic carbon concentration of the ultrasonified and filtered stock solution was analyzed with a TOC analyzer. The final concentrations in the test vessels were calculated based on the dilution factor. The algae were exposed to each concentration in triplicate. Six vessels were prepared for the control. The algae were incubated under standardized conditions (continuous light, controlled temperature) in an incubator shaker apparatus. As a parameter for the growth of the algae population, the algae cells were measured with a coulter counter. The growth rate was calculated on the basis of the cell counts.

The calculated growth rate of each concentration was compared to those of the controls, and the inhibition was calculated.

Imidazotriazinon had a concentration-depended inhibitory effect on the growth of Desmodesmus subspicatus. The ErC50(growth rate) was 11.354 mg/L [95 % confidence limits: 8.838-16.176] on the basis of measured concentrations. The NOEC was 0.93 mg/L, the LOEC was 1.86 mg/L.