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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
August 2018 - April 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
The saturated solution and the control were analytically verified via LC-MS/MS in the fresh media at the start of exposure and at the renewal of the test solutions (0 and 24 hours) as well as in the 24-hours old media at the renewal and at the end of the exposure (24 and 48 hours). The samples were analyzed with an LC-MS/MS method, implemented under non-GLP and documented finally in the GLP raw data.
Vehicle:
no
Details on test solutions:
A saturated solution with a nominal loading of 116 mg/L of the test item was prepared one day prior to the start of the exposure (at -24 hours) and the renewal of the test solutions (at 0 hours) in a glass flask. An appropriate amount of the test item was weighed out and transferred with an appropriate amount of the dilution water into the glass flask. This dispersion was stirred at approximately 1100 rpm for 24±1 hour at room temperature. After completion of stirring, the solution was centrifuged (14000 rpm, 15 minutes, 20 ± 2°C) for separation of undissolved test item. The saturated solution was checked via laser beam (Tyndall effect) for undissolved test item (formation of an emulsion / suspension). No Tyndall effect was observed in the saturated solution. For the renewal of the test solutions after 24 hours, a new approach was set up.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Strain: STRAUS
- Source: InstitutfurWasser-, Boden- und Lufthygiene (WaBoLu), 14195 Berlin, Germany
- Age at study initiation: < 24 h
- Feeding during test: none

CULTURE
- Culture Conditions: static; other conditions same as test
- Type and amount of food: at least 5 times per week ad libitum with a mix of unicellular green algae, e.g. Pseudokirchneriella subcapitata and Desmodesmus subspicatus. The algae were cultured at the test facility.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
236 - 267 mg/L CaCO3
Test temperature:
20.1 - 20.4 °C
pH:
7.43 - 7.64
Dissolved oxygen:
7.93 - 8.91 mg/L
Nominal and measured concentrations:
Nominal concentration: 116 mg/L, corresponding to 100 mg active substance/L
Geometric mean measured test item concentration: 1.70 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: beakers
- Type: loosely covered with watch glasses
- Material, size, fill volume: glass, 4 (ID) x 7 (H) cm, 50 mL, 20 mL
- Aeration: none
- Renewal rate of test solution: after 24 h
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4, according to OECD 202, Annex 3 (2004) is used.
- Culture medium different from test medium: no
- Intervals of water quality measurement: Temperature, dissolved oxygen and pH were measured at 0, 24 and 48 h.

OTHER TEST CONDITIONS
- Photoperiod: 16 h light/8 h dark
- Intensity: max. 1500 Iux

EFFECT PARAMETERS MEASURED
- Immobilisation of daphnids was recorded after 24 and 48 h of exposure.

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 0, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: 48 h EC50 > 100 mg/L.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 1.7 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
1.7 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: none
- Mortality of control: none
- Analytical monitoring: Please see table 1 for details.
No immobile daphnids were detected during the experiment.
The saturated solution was colorless and visually clear throughout the exposure. No Tyndall effect was observed in the saturated solution.
The study was performed according to OECD Guideline 202 (2004). The validity criteria were fulfilled:
• In the control group, no daphnids were immobilized or showed any signs of disease or stress, e.g. discoloration or unusual behavior such as trapping on the surface of the water, during the 48-hour test period (required: not more than 10% of the daphnids immobilized in the control).
• The dissolved O2 concentration in the 24-hours old media was ≥ 7.93 mg/L (required: ≥ 3 mg/L in the 24-hours old media) in the saturated solution and in the control.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Reference test period: 2018-08-07 to 2018-08-08
Result: 48 h EC50: 2.03 mg/L, 95%CL = 1.17 - 3.57 mg/L
Valid Range: 0.6 - 2.4 mg/L, acc. to AQS P 9/2 (02/2000): clone 5: 0.6 - 2.1 mg/L, acc. to OECD 202 (2004): clone A

Table 1: Measured Concentrationsof theTest Item during the Definitive Test

Sampling date

0 hours Fresh medium

24 hours Old medium

24 hours Fresh medium

48 hours Old medium

 

Dilution level of the saturated solution [%]

Test item

Meas. conc.[mg/L]

Meas. conc.[mg/L]

%

Meas. conc.[mg/L]

Meas. conc.[mg/L]

%

Geometric mean measured test

item concentration1) [mg/L]

100

1.55

1.08

70

2.82

1.77

63

1.70

Control

< LOQ

< LOQ

< LOQ

< LOQ

< LOQ

Meas. conc. = measured concentration of the test item, dilution factor taken into account

% = percent of the initial measured concentration of the test item

LOQ = Limit of Quantification (20 µg test item/L)

1)= The geometric mean measured test item concentration was calculated with the software Excel (Microsoft).

Validity criteria fulfilled:
yes
Conclusions:
The EC50 (48h) of the test item was determined according to OECD guideline 202 to be > 1.70 mg/L.
Executive summary:

To assess the toxicity of the test item to Daphnia magna, a semi-static acute toxicity test according to OECD guideline 202 was conducted in compliance with GLP principles. The study was conducted as a limit test under semi-static conditions over a period of 48 hours with a saturated solution of the test item with a nominal loading of 116 mg/L, corresponding to 100 mg active substance/L and the geometric mean measured concentration 1.70 mg/L. The saturated solution was colorless and visually clear throughout the exposure. No Tyndall effect was observed in the saturated solution. Twenty daphnids (divided into 4 replicates with 5 daphnids each) were exposed to the saturated solution and the control. The concentration of the test item was analytically verified via LC-MS/MS in the fresh media of the saturated solution and in the control at the start of the exposure and at renewal (0 and 24 hours) and in 24-hours old media at renewal and at the end of the test (24 and 48 hours). The measured concentration of the test item in the old media was between 63% and 70% compared to the measured concentration in the fresh media. The validity criteria of the test guidelines were fulfilled. As a result, the EC50 (48h) of the test item was determined to be > 1.70 mg/L and the NOEC (48h) was determined to be 1.70 mg/L. In conclusion, no effects occurred up to the test concentration of 1.7 mg/L (geometric mean measured concentration). The test is regarded as valid.

Description of key information

The EC50 (48h) of the test item was determined according to OECD guideline 202 to be > 1.70 mg/L (reference 6.1.3 -1).

Key value for chemical safety assessment

Additional information

To assess the toxicity of the test item to Daphnia magna, a semi-static acute toxicity test according to OECD guideline 202 was conducted in compliance with GLP principles (reference 6.1.3 -1). The study was conducted as a limit test under semi-static conditions over a period of 48 hours with a saturated solution of the test item with a nominal loading of 116 mg/L, corresponding to 100 mg active substance/L and the geometric mean measured concentration 1.70 mg/L. The saturated solution was colorless and visually clear throughout the exposure. No Tyndall effect was observed in the saturated solution. Twenty daphnids (divided into 4 replicates with 5 daphnids each) were exposed to the saturated solution and the control. The concentration of the test item was analytically verified via LC-MS/MS in the fresh media of the saturated solution and in the control at the start of the exposure and at renewal (0 and 24 hours) and in 24-hours old media at renewal and at the end of the test (24 and 48 hours). The measured concentration of the test item in the old media was between 63% and 70% compared to the measured concentration in the fresh media. The validity criteria of the test guidelines were fulfilled. As a result, the EC50 (48h) of the test item was determined to be > 1.70 mg/L and the NOEC (48h) was determined to be 1.70 mg/L. In conclusion, no effects occurred up to the test concentration of 1.7 mg/L (geometric mean measured concentration). The test is regarded as valid.