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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Endpoint:
effects on growth of green algae
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2022
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2022

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
Analytical monitoring was attempted but was not fully successfully owing to the extremely low solubility of the test substance and a suspected propensity to adhere to glassware
GLP compliance:
no
Remarks:
The study was undertaken according to GLP up until the point that the decision was made not to continue to the main test since sufficient results had been obtained through range-finding.

Test material

Constituent 1
Chemical structure
Reference substance name:
Glycerol tribenzoate
EC Number:
210-379-6
EC Name:
Glycerol tribenzoate
Cas Number:
614-33-5
Molecular formula:
C24H20O6
IUPAC Name:
1,3-bis(benzoyloxy)propan-2-yl benzoate
Test material form:
solid: flakes
Details on test material:
room temperature: off-white coloured flakes or granulate; > 80 °C: colourless to yellowish liquid
Batch no. 20118
CAS no. 614-33-5
Production date 28. Jul. 2020
Expiry date 15. Aug. 2022
Specific details on test material used for the study:
Batch: 20118
Expiry: 15 August 2022
Purity: 98.1%

Sampling and analysis

Analytical monitoring:
yes
Remarks:
Analytical monitoring was attempted but was not fully successfully owing to the extremely low solubility of the test substance and a suspected propensity to adhere to glassware

Test solutions

Vehicle:
no
Details on test solutions:
1st Pre-Test
A saturated solutions was prepared for the test. This was done by mixing the nominal load
of 100 mg/L with the corresponding amount of algal medium and shaking vigorously for 25
hours. After a settling time of 1 hour the resulting solutions were filtrated through 0.45 μm
PTFE-filters. The filtrated solution was clear and without undissolved particles of the test
item. The lower treatments (1 mg/L and 10 mg/L nominal) were prepared by dilution of these
saturated solution with the algal medium.

2nd Pre-Test
A saturated solution was prepared for the test. This was done by mixing the nominal load of
100 mg/L with the corresponding amount of algal medium and shaking vigorously for 23.25
hours. After a settling time of 30 minutes the resulting solution was centrifuged (4500 rpm,
10 min.) and the supernatant was used for the test. The tested supernatant was clear and
without undissolved particles of the test item.

3rd Pre-Test
This pre-test was conducted on sponsors request.
3 saturated solutions were prepared for the tests. This was done by mixing 3x the nominal
load of 100 mg/L with algal medium and shaking vigorously for 23 hours. Afterwards, the
saturated solutions were used for the test unfiltrated and uncentrifuged. Undissolved test
item was visible at the bottom of the test vessels. Every saturated solution was a separate
replicate.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Unicellular freshwater green alga.
Genus Desmodesmus
Species subspicatus
SAG Strain Number 86.81
Taxonomic position Chlorophyta - Chlorophyceae

Study design

Test type:
static
Water media type:
other: The algal medium corresponds to the OECD TG 201 medium.
Limit test:
yes
Total exposure duration:
72 h

Test conditions

pH:
1st Pre-Test : 7.7 - 9.3

3rd Pre-Test: 7.8 - 8.2
Nominal and measured concentrations:
The test material is extremely insoluble and this prohibited the use of a suitably sensitive validated method, despite all attempts.
Details on test conditions:
1st Pre-Test
Date of performance 02. – 05. Oct. 2020
Treatments 1 / 10 / 100 mg/L (nominal concentration)
Temperature 21.9 – 22.4 °C
Test vessels glass flasks total volume 65 mL
Replicates (Treatments) 3 vessels, each filled with 45 ± 1 mL test solution and algae
Replicates (Blank Control) 6 vessels, each filled with 45 ± 1 mL algal medium and algae

2nd Pre-Test
Date of performance 04. – 07. Dec. 2020
Treatment 100 mg/L (nominal concentration)
Temperature 21.0 – 21.6 °C
Test vessels glass flasks total volume 65 mL
Replicates (Treatment) 3 vessels, each filled with 45 ± 1 mL test solution and algae
Replicates (Blank Control) 6 vessels, each filled with 45 ± 1 mL algal medium and algae

3rd Pre-Test
Date of performance 15. – 18. Jan. 2021
Treatments 3x 100 mg/L (nominal concentration)
Temperature 20.8 – 22.7 °C
Test vessels glass bottles, nominal volume 250 mL
Replicates (Treatments) 3 bottles, each filled with 200 mL test solution and algae
Replicates (Blank Control) 6 bottles, each filled with 200 mL algal medium and algae

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 3rd Pre-Test
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 2nd Pre-Test
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 1st Pre-Test
Details on results:
A total of 18 control algal replicates and 9 replicates exposed to GTB at 100 mg/L were used in the test over three separate pre-tests. The number of organisms used adheres to the OECD TG 201 for a limit test study design.

Applicant's summary and conclusion

Conclusions:
The test material is extremely insoluble and this prohibited the use of a suitably sensitive validated method, despite all attempts.
Executive summary:

EC50 was detrmined to be >100mg/L