Registration Dossier

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:
2017-08-22 to 2017-12-08
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 guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
TEST MATERIAL
Name ( stated on the report) : TETRAHYDRO CITRAL
Appearance: Colourless to pale yellow liquid
Batch: SC00019145
Stable under storage conditions until: 18 March 2018 (expiry date)

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
The concentrations of the test item and the control were determined at the start of the exposure (0 hours) and at the end of the exposure (72 hours) via GC-MS.

Test solutions

Vehicle:
no
Details on test solutions:
A stock solution with a nominal concentration of 13 mg test item/L was freshly prepared with dilution water. For the preparation the density was taken into account. The stock solution was stirred for 60 minutes (1100 rpm, room temperature) with a magnetic stirrer until the test item was completely dissolved.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
- Origin: Sammlung von Algenkulturen (SAG) Pflanzenphysiologisches Institut der Universität Göttingen Nikolausberger Weg 18, D-37073 Göttingen
- Cultivation at test facility : Fresh stocks are prepared every month on Z-Agar. Light intensity amounted to 2567 - 5130 lux for 24 hours per day.
- Culture medium : Nutrient medium Z according to LOttge et al. (1994)

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h

Test conditions

Hardness:
0.24 mmol Ca+Mg/L
Test temperature:
Nominal range: 21 - 24°C, controlled at ± 2°C
pH:
7.97 to 9.65
Nominal and measured concentrations:
Nominal concentration: 0.130 - 0.411 - 1.30 - 4.11 - 13.0 mg/L
Geometric mean measured concentrations: 0.0214 - 0.0408 - 0.144 - 0.800 - 11.9 mg/L
Details on test conditions:
- Performance of the test: A static test was carried out. With regard to the volatility of the test item glass flasks without headspace were used to reduce losses of test item.
- Duration of the test: 72 hours
- Replicates: Three replicates per concentration level and six for the control Separate replicates for each measuring time were prepared.
- Test container: Sterile headspace flasks, volume: 59 mL, with aluminium tops with PTFE seals.
- Test volume : 59 mL
- Preculture: A three days old preculture, prepared in dilution water, was used as inoculum
- Incubation: The flasks were positioned randomly and repositioned daily.
- Temperature (target) : Nominal range: 21 - 24°C, controlled at ± 2°C
- Agitation: Test containers were placed on a rotary shaker and oscillated at approximately 70 rpm.
- Light intensity (target) : Approximately 4440 to 8880 lux, corresponding to 60 to 120 microE*m-2*s-1
- Light regime : 24 hours/day light
- Light homogeneity (target): Within ± 15% over incubation area
Reference substance (positive control):
yes
Remarks:
potassium dichromate (Sigma-Aldrich, batch number MKBV0900V, purity 99.0%, CAS RN 7778-50-9)

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
3.75 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.543 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
The reference item toxicity is in the valid range following test facility SOPs.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In this study, TETRAHYDRO CITRAL was found to inhibit the growth of the freshwater green alga Pseudokirchnerielia subcapitata after 72 hours with the following effect values (based on geometric mean measured test item concentration): The EC50-values with 95% confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 3.75 (3.49 - 4.01) mg/L and 0.787 (0.625 - 1.05) mg/L, respectively. The EC10-values with 95 % confidence intervals for inhibition of growth rate (ErC10) and yield (EyC10) after 72 hours were 0.543 (0.468 - 0.629) mg/L and 0.133 (0.0982 - 0.179) mg/L, respectively. The NOEC-values for both inhibition of growth rate and yield after 72 hours were 0.0408 mg/L, respectively.
Executive summary:

The toxicity of TETRAHYDRO CITRAL (Batch no: SC00019145) to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 266/2016 C.3 from 2017-08-28 to 2017-09-01, with the definitive exposure phase from 2017-08-28 to 2017-08-31 at the test facility. The aim of the study was the determination of NOEC, LOEC, EC10, EC20- and EC50-values of growth rate and yield over a period of 72 hours.

The study was conducted under static conditions with an initial cell density of 6839 cells/mL. A stock solution with a nominal concentration of 13 mg test item/L was freshly prepared with dilution water. For the preparation the density was taken into account. The stock solution was stirred for 60 minutes (1100 rpm, room temperature) with a magnetic stirrer until the test item was completely dissolved. The stock solution and further four dilution levels were tested in a geometrical series with a factor of Vi 0: 0.130 - 0.411 - 1.30 - 4.11 - 13.0 mg/L, corresponding to the geometric mean measured test item concentrations of 0.0214 - 0.0408 - 0.144 - 0.800 - 11.9 mg/L. Three replicates were tested for each test item concentration and six replicates for the control. The environmental conditions were within the acceptable limits.

The concentrations of TETRAHYDRO CITRAL were determined at the start of the exposure (0 hours) and at the end of the exposure (72 hours) of all concentration levels and the control via GC-MS/MS.

The measured concentrations of the test item at the start of the exposure were in the range of 71 to 102%. At test end, the test item concentrations were in the range of < LOQ to 82%. All effect values given are based on the geometric mean measured test item concentrations of TETRAHYDRO CITRAL.

TETRAHYDRO CITRAL was found to inhibit the growth of the freshwater green alga Pseudokirchnerielia subcapitata after 72 hours with the following effect values (based on geometric mean measured test item concentration): The EC50-values with 95% confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 3.75 (3.49 - 4.01) mg/L and 0.787 (0.625 - 1.05) mg/L, respectively. The EC10-values with 95 % confidence intervals for inhibition of growth rate (ErC10) and yield (EyC10) after 72 hours were 0.543 (0.468 - 0.629) mg/L and 0.133 (0.0982 - 0.179) mg/L, respectively. The NOEC-values for both inhibition of growth rate and yield after 72 hours were 0.0408 mg/L, respectively.