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Ecotoxicological information

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:
Study completed on 16 May 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report date:
2017

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Methyl oct-2-ynoate
EC Number:
203-836-6
EC Name:
Methyl oct-2-ynoate
Cas Number:
111-12-6
Molecular formula:
C9H14O2
IUPAC Name:
methyl oct-2-ynoate
Test material form:
liquid

Sampling and analysis

Analytical monitoring:
no
Details on sampling:
For determination of the appropriate test concentrations for the main test, a range-finding test with nominal test item concentrations of 0.25, 2.5 and 25 mg/L was performed. For this, three replicates per treatment were tested. The test medium of the highest concentration of 25 mg/L was stirred until dissolution for 1 hour at room temperature in the dark. The test media of the two lower concentrations were prepared in a series of further dilution steps.

For the determination of the actual test item concentrations, duplicate samples were taken from each treatment at the start of the test.

After 24 hours and at the end of the test (after 72 hours), stability samples (containing algae) were taken in duplicate from all test concentrations and from the control.

The stability samples at 24 hours could not be taken from the test vessels itself, as the principle of a closed system is, that the test vessels have to remain completely filled with test medium during the entire test period. Therefore, for this sampling at 24 hours, a set of additional flasks containing the corresponding test medium (with algae) was incubated under conditions identical to the test.

For sampling at the end of the test, the test medium of the treatment replicates was pooled.

All samples were stored frozen (at -20 ± 5 °C) immediately after sampling. Based on pre-experiments for investigation of the storage stability, the test item was found to be stable in the test water under these storage conditions (see Analytical Procedure, Appendix 1).

The concentrations of FOLIONE were analytically measured in one of the duplicate samples taken from the control and all test concentrations from the start, 24 hours and end of the test.

Test solutions

Vehicle:
no
Details on test solutions:
Based on the results of the range-finder, the following nominal concentrations of FOLIONE were selected for the main test: 0.068, 0.15, 0.33, 0.72, 1.6 and 3.5 mg/L, applying a spacing factor of 2.2. The main test was performed in a closed system. Additionally, a control (test water without test item) was tested in parallel.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:

The test was started using a nominal algal cell density of 5000 cells/mL. The initial cell density was selected according to the recommendations of the OECD test guideline. The algal cell density in the pre-culture was determined using an electronic particle counter (Coulter Counter, Model Z2).

Study design

Test type:
static
Water media type:
other: Reconstituted test water (AAP Medium) prepared according to the test guidelines was used for algal cultivation and testing. Analytical grade salts were dissolved in sterile purified water.
Limit test:
no
Total exposure duration:
72 h

Test conditions

Hardness:
15 mg/L as CaCO3
Test temperature:
The water temperature during the test was maintained at 22 °C.
pH:
The pH of the test media was in the range of 7.5 to 7.8 during the test period.
Nominal and measured concentrations:
The measured concentrations of FOLIONE in the test media of the nominal test concentrations of 0.068 to 3.5 mg/L were between 82 and 85% of the nominal values at the start of the test. Thus, the correct dosage of the test item could be verified. During the test period, the test item concentrations in the test media decreased and were between
The Time-Weighted mean measured concentrations determined over the course of the 72 hour exposure were 0.012, 0.063, 0.13, 0.30, 0.88 and 2.4 mg/L, respectively, at the 0.068, 0.15, 0.33, 0.72, 1.6 and 3.5 mg/L (nominal) test concentrations.
Reference substance (positive control):
yes
Remarks:
Potassium DiChromate

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.79 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CI: 0.75 - 0.85 mg/L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.2 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CI: 0.18 - 0.23 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.063 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.32 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Remarks on result:
other: 95% CI: 0.30 - 0.33 mg/L
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.12 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Remarks on result:
other: 95% CI: 0.11 - 0.13 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.012 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
other: Yield
Results with reference substance (positive control):
For evaluation of the algal quality and experimental conditions, potassium dichromate is tested as a positive control twice a year to demonstrate satisfactory test conditions. The 72-hour EC50 for growth rate in the reference test IES Study Number 20160277 was 0.9 mg/L (October 2016) and showed that the sensitivity of the test system was within the range recommended by the guideline (72-hour EC50 for the growth rate 0.9 - 1.5 mg/L).

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Executive summary:

A clear concentration-response relationship was observed for both biological endpoints growth rate and yield during the exposure period.

Based on the results of the study, the :

EC50 (growth rate - 72 hr) = 0.79 mg/L

EC10 (growth rate - 72 hr) = 0.20 mg/L

NOEC (growth rate - 72 hr) = 0.063 mg/L

EC50 (yield - 72 hr) = 0.32 mg/L

EC10 (Yield - 72 hr) = 0.12 mg/L

NOEC (Yield - 72 hr) = 0.012 mg/L