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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:
From the 1st of February to the 3rd of February, 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:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
The temperature was kept at 23-24 °C (instead 18–22 °C), controlled at ±1 °C. This deviation had no influence
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
At the beginning of the test, as well as after 24 and 48 h of exposure.

Test solutions

Vehicle:
yes
Details on test solutions:
Elendt M4 medium

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
Daphnia magna (Straus, 1820) derived from a healthy stock and not first brood progeny
Age: less than 24 h
TEST SYSTEM
Breeding: parental and young Daphnia held in 4 L glass aquaria (3 L medium) at 20 ± 2 °C
Illumination: 16 h photoperiod a day, supplied by overhead white fluorescent tubes
Medium: continuously aerated Elendt M4 medium; prepared with ultra-pure water (conductivity <1.5 µS/cm)
Feed: Suspension of Desmodesmus subspicatus (green algae) in Elendt M4 medium with an optical density OD680 of about 15 units
Control of sensitivity: acute reference test with potassium dichromate conducted twice a year

Study design

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

Test conditions

Test temperature:
20.3 - 20.6 °C
Determined in an additional flask without Daphnia at the beginning of the test and after 24 and 48 h of exposure.
pH:
6.5 - 7.0
Determined in the combined test solutions for each concentration at the beginning and after 48 h of exposure.
Dissolved oxygen:
7.6 - 8.2 mg/L
Determined in the combined test solutions for each concentration at the beginning and after 48 h of exposure.
Conductivity:
822 - 958 µS.cm-1
Determined in the combined test solutions for each concentration at the beginning of the exposure.
Nominal and measured concentrations:
Based on the results of this non-GLP range finding test, the nominal test concentrations for the definitive test were
200 mg/L
100 mg/l test item,
corresponding to 121 and 60.4 mg/L, respectively, active ingredient.
The 200 mg/L test concentration was chosen in order to cover a broader concentration range, as the final purity of the test item was not yet known when the definitive test started.
Details on test conditions:
Test vessel: 100 ml flasks, all-glass, with 50 ml of test medium, covered with a glass plate to avoid evaporation and contamination of the test solutions with dust
N. Daphia: 40 individuals per test concentration, 20 per vessel
Light: 16 h photoperiod a day, supplied by overhead white fluorescent tubes
Feed: the Daphnia are not fed during the test

All values apart from the temperature were within the acceptable range.
The temperature was kept at 23-24°C and therefore not within the required range of 18–22 °C, controlled at ±1°C. This deviation had no influence on the outcome of the test results since no mortality was observed in the blank control and all other validity criteria were fulfilled.


Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
103 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
103 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Details on results:
The concentrations o in the test medium were measured by photometry at the beginning and after 24 and 48 h of exposure. These analyses revealed that the concentrations of the test item did not correspond to 80-120% of the nominal concentrations throughout the test (ranging between 74 % and 91%), but that the concentrations were stable (within 80-120% of the initially measured concentrations). The measured concentrations of the active ingredient at the beginning of the test were 103 and 55.2 mg/L; and 89.8 and 53.3 mg/L (i.e. respectively 87 and 97% of the initial value) after 48 hours of exposure.
The effective concentrations ECx were assessed based on the initially measured concentrations of the active ingredient.

No significant effects (≤10% immobilization) were observed at the nominal concentrations of 60.4 and 121 mg/L active ingredient or in the blank controls, neither after 24 h of exposure nor after 48 h.
The NOEC values after 24 h and after 48 h of exposure were both 103 mg/l based on the measured concentrations of the active ingredient.
Results with reference substance (positive control):
Acute reference test with potassium dichromate conducted twice a year.
The EC50 value for the control of sensitivity for 24 h of exposure with potassium dichromate was estimated to be 0.89 mg/L (data from 29 June 2016), which lies within the recommended range of 0.6–2.1 mg/L according to OECD Guideline 202.
Reported statistics and error estimates:
Statistical analysis was performed with respect to the effect concentrations (including 95% confidence limits)

Any other information on results incl. tables

The effect concentration ECx is the concentration leading to immobilization of x % of the Daphnia after 24 or 48 h of exposure. Those individuals not able to swim within 15 s after gentle agitation of the test vessel were considered to be immobile (even if they were still able move their antennae). The effect concentration ErC50 and EyC50 were determined with ToxRat® Standard Version 2.10 (ToxRat® Solutions GmbH, Alsdorf, Germany).

The no observed effect concentration (NOEC) is the highest concentration tested for which the observed effect is not significantly different from the blank controls. Immobilization rates of <=10% are regarded as not biologically significant.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
A test is considered valid if not more than 10% of the Daphnia in the control were immobilized, trapped at the surface of the water, or showed any signs of disease or stress. The dissolved oxygen concentration at the end of the test has to be ≥3 mg O2/L.
Conclusions:
EC50 Daphnia magna (24h): 103 mg/L
EC50 Daphnia magna (48h): 103 mg/L
Executive summary:

Method

The median effect concentration (EC50) and the no-effect concentration (NOEC) of the substance to Daphnia magna were investigated under static exposure conditions over a period of 48 h, following the guideline OECD 202. Since the test item proved to be only partially soluble in Daphnia medium, the test solutions were prepared as WSFs (water soluble fractions). The investigated concentrations were 300, 136, 62.0, 28.2 and 12.8 mg/L loading rate of the test item, corresponding to 219, 99.8, 45.3, 20.6 and 9.37 mg/L of the active ingredient.

40 individual Daphnia divided into 2 test vessels were expose to each concentration of the test item, and 60 Daphnia divided into 3 test vessels were used as blank controls. The test concentrations during the 48 h test period were measured by HPLC analysis, confirming that the test item was only partially soluble in Daphnia medium and that the concentrations of the test item were satisfactorily maintained over the whole 48 h test period. The effective concentrations ErCx/EyCx were assessed based on the geometric mean (GM) of the measured concentrations of the active ingredient.

Observations

No significant effects (≤ 10% immobilization) were observed at the nominal concentrations of 60.4 and 121 mg/L active ingredient or in the blank controls, neither after 24 h of exposure nor after 48 h.

Conclusion

The median effect concentrations (EC50) on Daphnia magna after 24 h as well as after 48 h of exposure were estimated to be >103 mg/L.

All validity criteria were fulfilled.