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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
2-[2,4-bis(tert-pentyl)phenoxy]-N-(3,5-dichloro-4-ethyl-2-hydroxyphenyl)butyramide
EC Number:
300-634-0
EC Name:
2-[2,4-bis(tert-pentyl)phenoxy]-N-(3,5-dichloro-4-ethyl-2-hydroxyphenyl)butyramide
Cas Number:
93951-12-3
Molecular formula:
C28H39Cl2NO3
IUPAC Name:
2-[2,4-bis(tert-pentyl)phenoxy]-N-(3,5-dichloro-4-ethyl-2-hydroxyphenyl)butyramide
Test material form:
solid
Details on test material:
Batch 44029
colour : White to off-white
retest date : 01/06/2019
Specific details on test material used for the study:
Storage conditions: Controlled room temperature (15-25°C, ≤70% relative humidity), protected from light and humidity (store in a tightly closed container)

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Duplicate samples (from three replicates) were taken (2 x ~2 mL) in glass tubes at the beginning and at the end of the renewal periods from the control and at the applied test concentration level.
After sampling, samples were frozen and kept approximately at -20°C at the Test Facility. One set of the samples was sent to the Test Site for analysis and one set was retained as a back-up at the Test Facility, if required for any confirmatory analyses (discarded after satisfactory results were obtained on the first set of).

Test solutions

Vehicle:
yes
Remarks:
Reconstituted water
Details on test solutions:
Because the test item was poorly soluble in water, test solutions were prepared using a saturated solution method according to the Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, OECD No. 23.
A saturated test item solution (nominal loading rate of 100.0 mg/L) was prepared by dispersing/dissolving the amount of test item 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.
The test solution was prepared just before introduction of the Daphnia (start of the treatments).

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
Number of animals: There were 20 animals in test group and control group respectively, divided into 4 replicates (5 animals / replicate)
Age of the animals: They were less than 24 h old at the beginning of the test
Acclimatization: There was no acclimatization because the water used was similar to the culture water.

Study design

Test type:
semi-static
Water media type:
other: Reconstituted water (ISO medium, according to OECD 202) was used as dilution water for both the range finding and definitive tests.
Limit test:
yes
Total exposure duration:
48 h

Test conditions

Hardness:
The reconstituted water (ISO medium) had a total hardness of 247 mg/L (as CaCO3).
Test temperature:
The water temperature was measured at the start and at the end of the renewal periods in each test vessel. The test temperature was in the range of 20.2 – 20.7°C measured in the test vessels.
The additionally measured temperature in the climate chamber was between 19.5 – 21.0°C.
pH:
The pH of the test solution was not adjusted and not varied by more than 1.5 units in any one test. The pH was measured at the start and at the end of the renewal periods in each test vessel and was in the range of 7.75 – 7.83.
Dissolved oxygen:
The dissolved oxygen concentration was measured in each test vessel at the start and at the end of the renewal periods and was in the range of 7.4 – 8.6 mg/L.
Nominal and measured concentrations:
Analysis of the test medium was performed at the start and at the end of the renewal periods, but the test item concentration could not be measured. The measured concentration was below the Limit of Detection (LOD = 0.01 μg/L) during the whole experiment. The biological results are based on the nominal test item concentration.
Details on test conditions:
Light: The test was carried out in 16-hour light and 8-hour dark cycle.
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
In addition to immobility, no abnormal behaviour or appearance of test animals was detected.

Although 5 % immobilization could be observed in the test item treated group, this difference is not considered significant as the test guideline states that the accepted control immobilization is 10 %.
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: 19/009-023DA) with reference item Potassium dichromate (batch no.: A0345704) is: 23 - 24 January 2019.
The 24h EC50: 0.71 mg/L, (95 % confidence limits: 0.66 – 0.75 mg/L)

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Based on the results of this study, the test item 80ACQ had no toxic effect at saturation; the EC50 results and the LOEC are higher than the solubility level of the test item in the test medium.
Executive summary:

Acute toxicity of 80ACQ on Daphnia magna was assessed 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 item in the test medium (100 mg/L nominal loading rate, 100 % saturated solution) and one control group in the definitive test.

Analysis of the test medium was performed at the start and at the end of the renewal periods, but the test item concentration could not be measured. The measured concentration was below the Limit of Detection (LOD = 0.01 μg/L) during the whole experiment. The biological results are based on the nominal test item 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 during this study.

Under the conditions of this Daphnia magna acute immobilisation study the observed endpoints for the effect of 80ACQ were the followings:

The 24h and 48h EC50 value: > 100.0 mg/L nominal loading rate

The 48h EC100 value: > 100.0 mg/L nominal loading rate

The 48h No-Observed Effect Concentration (NOEC): 100.0 mg/L nominal loading rate

The 48h Lowest Observed Effect Concentration (LOEC): > 100.0 mg/L nominal loading rate