1-Ethoxy-2,3-difluoro-4-(trans-4-propylcyclohexyl)-benzene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Oct 06- Nov 20, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 2006-03-23, corrected 2011-07-28

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

The test medium (reconstituted water and test item) was prepared freshly. Therefore, the calibrated flask with test medium was treated in an ultrasonic device for 1 hour. Subsequently, the preparation was stirred with a magnetic stirrer for further 23 hours. Afterwards, the formulation was passed through a membrane filter with a pore size of 0.2 µm. The filtrate was used for the study.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green algae
- Strain: Desmodesmus subspicatus
- Source (laboratory, culture collection): laboratory
- Age of inoculum (at test initiation): freshly prepared
- Method of cultivation: standard

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): same
- Any deformed or abnormal cells observed: none

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

-

Hardness:

250 mg/L

Test temperature:

23 °C

pH:

7.8 - 9

Nominal and measured concentrations:

nominal: 100.0 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 6 replicates with and 1 replicate without algae
- Type: open
- Initial cells density: 10000 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6
GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:
mg/L
NH4Cl: 15.0
MgCl2 * 6 H2O: 12.0
CaCl2 * 2 H2O: 18.0
MgSO4 * 7 H2O: 15.0
KH2PO4: 1.6
FeCl3 * 6 H2O: 0.064
Na2EDTA * 2 H2O: 0.10
H3BO3: 0.185
MnCl2 * 4 H2O: 0.415
ZnCl2: 0.003
CoCl2 * 6 H2O: 0.0015
CuCl2 * 2 H2O: 0.00001
Na2MoO4 * 2 H2O: 0.007
NaHCO3: 50.00
The pH of the reconstituted water after aeration is approximately 8.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

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

Results with reference substance (positive control):

The sensitivity of the test system has to be demonstrated periodically using potassium dichromate. Under the given experimental conditions, the test item potassium dichromate showed 72h EC values which are within the recommended range (Yield EC50 0.34 mg/L (95 % confidence interval: 0.31 – 0.36 mg/L) and Growth rate EC50 of 0.72 mg/L (0.60 –1.03 mg/L)).

Validity criteria fulfilled:

yes

Conclusions:

The 72h EC50 value in algae for the test item was > 100 mg/L (nominal) for growth rate and for yield.

Executive summary:

The objective of this study was to determine the influence of the test item on the growth and growth rate of the unicellular green algal species Desmodesmus subspicatus. The study design included one control group and one test material group with six replicates, each containing 100 mL reconstituted water or test medium and about 10000 cells/mL at the start of the experimental phase. The study was performed as a limit test in an open static test system. The algae were exposed to s filtrate of nominal 100 mg test material per L. The growth of the algae was calculated after 24, 48, and 72 hours exposure in the test item and control groups. This study was performed according to GLP and the methods applied are fully compliant with OECD 201.

The test material concentration in the reconstituted water was not quantified at the start and the end of this study due to the low water solubility (< 0.13 mg/L). Because of the low water solubility, the compound cannot be detected with standard analytical methods. The development of an analytical method with a sufficiently low detection and quantification limit is complex. Due  to  the absence of any adverse effects at the saturation concentration, the study was performed without analytical concentration verification.

EC values:

For the test item, the following values for Desmodesmus subspicatus were determined:

 

Parameter (0-72 h)	Growth rate	Yield
EC10	> 100 mg/L (nominal)	> 100 mg/L (nominal)
EC20	> 100 mg/L (nominal)	> 100 mg/L (nominal)
EC50	> 100 mg/L (nominal)	> 100 mg/L (nominal)
NOEC	> 100 mg/L (nominal)	> 100 mg/L (nominal)
LOEC	> 100 mg/L (nominal)	> 100 mg/L (nominal)

Under the conditions of the present study, the 72h EC₅₀ value in algae for the test item was > 100 mg/L (nominal) for growth rate and for yield, respectively

Description of key information

The 72h EC₅₀ value in algae for the test item was > 100 mg/L (nominal) for growth rate and for yield.

Additional information

The objective of this study was to determine the influence of the test item on the growth and growth rate of the unicellular green algal species Desmodesmus subspicatus. The study design included one control group and one test material group with six replicates, each containing 100 mL reconstituted water or test medium and about 10000 cells/mL at the start of the experimental phase. The study was performed as a limit test in an open static test system. The algae were exposed to s filtrate of nominal 100 mg test material per L. The growth of the algae was calculated after 24, 48, and 72 hours exposure in the test item and control groups. This study was performed according to GLP and the methods applied are fully compliant with OECD 201.

The test material concentration in the reconstituted water was not quantified at the start and the end of this study due to the low water solubility (< 0.13 mg/L). Because of the low water solubility, the compound cannot be detected with standard analytical methods. The development of an analytical method with a sufficiently low detection and quantification limit is complex. Due  to  the absence of any adverse effects at the saturation concentration, the study was performed without analytical concentration verification.

EC values:

For the test item, the following values for Desmodesmus subspicatus were determined:

 

Parameter (0-72 h)	Growth rate	Yield
EC10	> 100 mg/L (nominal)	> 100 mg/L (nominal)
EC20	> 100 mg/L (nominal)	> 100 mg/L (nominal)
EC50	> 100 mg/L (nominal)	> 100 mg/L (nominal)
NOEC	> 100 mg/L (nominal)	> 100 mg/L (nominal)
LOEC	> 100 mg/L (nominal)	> 100 mg/L (nominal)

Under the conditions of the present study, the 72h EC₅₀ value in algae for the test item was > 100 mg/L (nominal) for growth rate and for yield, respectively.