ethyl (3-benzoyl-2,4,6-trimethylbenzoyl)(phenyl)phosphinate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 November 2019 to 13 November 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

2017

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples were taken from the control and at the applied test concentration level at the beginning and at the end of the renewal periods. The test material samples were properly diluted into the calibration range with diluent and analysed by an HPLC system with UV detection method.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
Because the test material is considered to be poorly soluble in water, test material stock solution was prepared using a saturated solution method according to the Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, OECD No. 23.
Saturated test material solution (nominal loading rate of 100.0 mg/L) was prepared by dispersing/dissolving the amount of test material into the test medium (ISO Medium) two days before the start of the experiment. This solution was shaken for about 24 hours at approximately 30 °C and then equilibrated for about 24 hours at approximately 20 °C. The non-dissolved test material was removed by filtration through a fine (0.22 µm) filter to give the appropriate 100 % saturated solution.
As a limit test was carried out, further dilution of stock solution was not performed.

Test material solution was prepared fresh for each renewal using the method described above. The test solution was prepared just before introduction of the Daphnia (start of the treatments).

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Age at study initiation: Daphnids were less than 24 h old at the beginning of the test.
- Justification for species other than prescribed by test guideline: Daphnia magna is the standard species of the acute immobilisation test.
- Feeding during test: The animals were not fed during the test.

ACCLIMATION
- Acclimation period: There was no acclimatisation because the water used was similar to the culture water.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

246 mg/L (as CaCO3)

Test temperature:

20.4 - 20.9 °C (test vessels), 20.3 - 20.9 °C (climate chamber)

pH:

7.20 - 7.87

Dissolved oxygen:

7.4 - 8.5 mg/L

Nominal and measured concentrations:

100 mg/L (nominal), 0.995 mg/L (measured geometric mean)

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL glass beaker
- Fill volume: ~ 40 mL (8 mL test solution/ animal)
- Renewal rate of test solution: The frequency of the water renewal periods was 24 hours.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Renewal rate of test solution: Based on the analytical method validation, the test was performed under semi-static conditions. The frequency of the water renewal periods was 24 hours.

TEST MEDIUM / WATER PARAMETERS
Reconstituted water (ISO medium, according to OECD 202) was used as dilution water for both the range finding and definitive tests. The same composition of reconstituted water was used for the tests and for breeding the test animals.
- Composition of dilution water: Separate stock solutions of individual trace elements were first prepared in deionised water. The medium was prepared of these different stock solutions, so it contained all trace elements (combined solution), as follows:
25 mL CaCl2.2H2O (11.76 g/L), 25 mL MgSO4.7H2O (4.93 g/L), KCl (0.23 g/L), NaHCO3 (2.59 g/L), made up to 1L with deionised water.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light / 8 hours dark cycle.
- Adjustment of pH: The pH of the test solution was not adjusted and not varied by more than 1.5 units in any one test.
- The water temperature, the oxygen concentrations and pH of the control and the test solution were measured at the beginning and at the end of the renewal periods.

EFFECT PARAMETERS MEASURED
The immobility or mortality of the Daphnia was determined by visual observation 24 and 48 hours after the start of the test. Those animals not able to swim within 15 seconds after gentle agitation of the test beaker are considered to be immobile.
The number of immobilised animals and the percentage of immobility were determined at 24 and 48 hours.

VEHICLE CONTROL PERFORMED: Not applicable.

RANGE-FINDING STUDY
- Test concentrations: 0, 0.1, 1, 10, 100 % saturated solution
- Results used to determine the conditions for the definitive study: Yes.
A concentration range-finding test was conducted to determine the approximate toxicity of the test material so that appropriate test concentrations could be selected for use in the definitive test. Ten daphnids (divided into two replicates) in each test concentration and control were exposed for 48 hours under semi-static conditions (in absence of stability data).
Because a toxic response was not observed during the preliminary concentration range-finding test, a limit test was carried out using only one test concentration at the solubility level of the test material in the test medium (100 mg/L nominal loading rate) and one control group in a semi-static system.
The biological results are based on measured geometric mean test material concentrations.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.995 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Concentrations of the test material
A limit test was performed at 100 mg/L nominal loading rate (the solubility level of the test mateiral), a control group was run in parallel.
The test concentration was analytically determined at the start and at the end of the renewal periods.
The measured test material concentration was 1.757 and 1.557 mg/L at the start of the renewal periods, while 0.863 and 0.415 mg/L was measured at the end of the periods. The corresponding measured geometric mean test material concentration was 0.995 mg/L during the experiment.
The biological results are related to the measured geometric mean test material concentration.

- Immobilisation
None of the animals were determined to be immobilised during the study. Furthermore, no abnormal behaviour or appearance of test animals was detected.

- Behavioural abnormalities
No abnormal behaviour or appearance of test animals was detected.

- Validity criteria
There were no immobilised animals in the control group and the dissolved oxygen concentration at the end of the test in the control and test vessels was more than 3 mg/L.
All validity criteria were within acceptable limits and therefore the study can be considered as valid.

Results with reference substance (positive control):

For the evaluation of the quality of the Daphnia clone and the experimental conditions, potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.
The date of the last study (Study Code: 19/238-023DA) with reference item potassium dichromate (batch no.: A0345704) is: 05 - 06 September 2019.
The 24h EC50: 0.82 mg/L, (95 % confidence limits: 0.66 – 0.93 mg/L)

Reported statistics and error estimates:

No statistical analysis was performed because of the lack of toxic effects.
The EC50, NOEC, LOEC and EC100 values were determined directly from the raw data.

Calculation of Exposure Concentrations

Nominal Concentration (% saturated solution)	Measured Concentrations (mg/L) 1st Renewal Period		Measured Concentrations (mg/L) 2nd Renewal Period		Geometric Mean
	fresh	aged	fresh	aged	mg/L
Control	n.d.	n.d.	n.d.	n.d.	-
100.0	1.757	0.863	1.557	0.415	0.995

n.d.: not detected

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study, the 48-hour EC50 was determined to be > 100 mg/L (nominal), > 0.995 mg/L (measured geometric mean).
Based on the results of this study, it can be concluded that the test material had no toxic effect at saturation (0.995 mg/L, measured); the EC50 results and the LOEC are higher than the solubility level of the test material in the test medium.

Executive summary:

The acute toxicity of the test material to Daphnia magna was assessed in a study which was conducted in accordance with the standardised guidelines OECD 202, EU Method C.2 and EPA OPPTS 850.1010, under GLP conditions in an acute immobilisation test, over an exposure period of 48 hours in a semi-static test system.

Because no toxic response was observed during the preliminary range-finding test, a Limit Test was carried out using only one test concentration at the solubility level of the test material in the test medium (100 mg/L nominal loading rate) and one control group in the definitive test.

The test concentration was analytically determined at the start and at the end of the renewal periods. The measured test material concentration was 1.757 and 1.557 mg/L at the start of the renewal periods, while 0.863 and 0.415 mg/L was measured at the end of the periods. The corresponding measured geometric mean test material concentration was 0.995 mg/L during the experiment.

The biological results are based on measured geometric mean test material concentration.

Twenty animals, divided into four groups (glass beaker) of five animals each were used at the test concentration and for the control.

All validity criteria were met.

Under the conditions of the study, the 48 -hour EC50 was determined to be > 100 mg/L (nominal), > 0.995 mg/L (measured geometric mean).

Based on the results of this study, it can be concluded that the test material had no toxic effect at saturation (0.995 mg/L, measured); the EC50 results and the LOEC are higher than the solubility level of the test material in the test medium.

Description of key information

The acute toxicity of the test material to Daphnia magna was assessed in a study which was conducted in accordance with the standardised guidelines OECD 202, EU Method C.2 and EPA OPPTS 850.1010, under GLP conditions in an acute immobilisation test, over an exposure period of 48 hours in a semi-static test system.

 

Under the conditions of the study, the 48-hour EC50 was determined to be > 100 mg/L (nominal), > 0.995 mg/L (measured geometric mean).

 

Based on the results of this study, it can be concluded that the test material had no toxic effect at saturation (0.995 mg/L, measured); the EC50 results and the LOEC are higher than the solubility level of the test material in the test medium.