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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:
2019-02-22 to 2019-05-15
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)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 100, 45.5, 20.7, 9.39, 4.27 mg/L (nominal)
- Sampling method: Analytical samples were taken from all test item loading rates and control at test start and after 24 hours from fresh and aged solutions and after 48 hours from aged solutions. For each sampling also a retain sample was taken.
- Sample storage conditions before analysis: All samples were stored deep frozen until they were transferred to the analytical laboratory.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Due to the low water solubility of the test item, it was applied as water accommodated fraction (WAF). Stock solutions S1 to S5 were prepared by directly weighing the necessary amount of test item on a weighing scoop and transferred to a volumetric flask. Test medium was added up to the bench mark and the stock solutions were stirred for 48 h and let settle down for 24 h (based on OECD Series on Testing and Assessment No. 23). The solution was clear and transparent and the test item was visible on the water surface and at the bottom of the glass vessels. After the settling phase, the necessary volumes for the test were withdrawn via a Teflon tube from the medium level of the stock solutions. The preparation procedure was repeated the same way and from the same technician after 24 hours. ≥ 50 mL of the prepared solutions were transferred to each test vessel.
- Eluate: N/A
- Differential loading: N/A
- Controls: The control was untreated test medium
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): N/A
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): N/A
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): During preparation: see above; Appearance of the Test Item in Test Medium: No remarkable observations.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna (Straus)
- Strain/clone: Clone V
- Justification for species other than prescribed by test guideline: N/A
- Age at study initiation (mean and range, SD): max. 24 hours old
- Feeding during test : No
- Reference Item: For the evaluation of the quality of the Daphnia clone and the consistency of the experimental conditions, the reference item potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.

ACCLIMATION
- Acclimation period: N/A
- Acclimation conditions (same as test or not): N/A
- Type and amount of food: N/A
- Feeding frequency: N/A
- Health during acclimation (any mortality observed): N/A

QUARANTINE (wild caught)
- Duration:
- Health/mortality:
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
13°dH (232 mg/L CaCO3)
Test temperature:
18.8 – 21.0 °C
pH:
7.05 – 8.02
Dissolved oxygen:
≥ 8.2 mg/L
Nominal and measured concentrations:
The measured content of test item was between 1 % and 14 % of nominal in the fresh samples with a mean initial concentration of 5 % of nominal. In the aged samples the measured content was between 3 % and 12 % of nominal with a mean measured concentration of 7 % of nominal.
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL glass beakers, each filled with ≥ 50 mL
- Type (delete if not applicable): open
- Aeration: No
- Type of flow-through (e.g. peristaltic or proportional diluter): Semi-static, no flow-through
- Renewal rate of test solution (frequency/flow rate): 24 h
- No. of organisms per vessel: 20 per treatment in 4 replicates of 5
- Replicates: The test was performed with four replicates per treatment group.
- Exposure Time: 48 hours
- 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: Purified water
- Test medium: Reconstituted test water (ISO water; OECD test guideline 202 (2004)
- Culture medium different from test medium: Yes
- Light Regime: 16 h light : 8 h dark
- Light intensity:

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobility. After 24 h and 48 h the immobilised daphnids were counted. All daphnids not able to swim within 15 seconds after gentle agitation of the test vessel were considered to be immobilised.

VEHICLE CONTROL PERFORMED: N/A

RANGE-FINDING STUDY
- Test concentrations: 100, 45.5, 20.7, 9.39, 4.27 mg/L and control
- Results used to determine the conditions for the definitive study: Yes
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
NOELR
Effect conc.:
9.39 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
43.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
2 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 2 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities:
- Observations on body length and weight: No
- Other biological observations: No
- Mortality of control: No mortality occured in the control
- Other adverse effects control: No
- Immobilisation of control: No immobilisatio occured in the control
- Abnormal responses: No
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No
- Effect concentrations exceeding solubility of substance in test medium:
Results with reference substance (positive control):
IIn order to check the validity of the results, the toxicity of the reference item potassium dichromate was tested at 0.6 and 2.1 mg/L with 20 test organisms per test concentration. Since the results are in accordance with the requirements of the OECD guideline 202 and fall within the historical data generated with the reference item at the testing facility, the daphnids were suitable for the determination of the toxicological effects of the test item.
In the reference test performed in June 2017 (study code 88298220) with the reference item potassium dichromate, the EC50 after 24 hours was determined to be 1.58 mg test item/L and the EC50 after 48 hours was determined to be 1.07 mg test item/L.
Reported statistics and error estimates:
The values for EL50/EC50 were determined by Probit analysis using linear max. likelihood regression. The NOELR/NOEC was established based on the highest loading rate/concentration at which the immobilisation is not higher than the allowed control immobilisation (≤ 10 % immobilisation).

Validity criteria of the study

Control immobilisation

The percentage of immobilisation should be ≤ 10 %. In this study the control immobilisation was 0 %.

Oxygen concentration

The dissolved oxygen concentration at the end of the test should be ≥ 3 mg/L in all test units. In this test, the dissolved oxygen concentration at the end of the test was ≥ 8.2 mg/L.

 

 

Biological results

EL50 and NOELR-values of daphnids exposed to the test item evaluated using nominal loading rates

Endpoint

LYSO[mg/L]

 

24h

48 h

NOELR

100

20.7

EL50

> 100

46.3

95 % confidence limit of EL50

-

37.8 – 56.7

 

EC50 and NOEC-values of daphnids exposed to the test item evaluated using actual test item concentrations

Endpoint

LYSO[mg/L] (actual1))

 

24 h

48 h

NOEC

2.00

1.66

EC502)

> 2.00

1.66

95 % confidence limit of EC50

-

n.d.

 

 

 

Analytical Results

 

 

The measured content of test item was between 1 % and 14 % of nominal in the fresh samples with a mean initial concentration of 5 % of nominal. In the aged samples the measured content was between 3 % and 12 % of nominal with a mean measured concentration of 7 % of nominal.

Validity criteria fulfilled:
yes
Conclusions:
In an acute toxicity test conducted according to the OECD guideline 202 Daphnia magna were exposed to test item loading rates of 100, 45.5, 20.7, 9.39, 4.27 mg/L (nominal) LYSO. According to the results of the test, the EL50 (48 h) was determined to be 43.1 mg/L (nominal). The corresponding NOELR (48 h) was 9.39 mg/L (nominal). The EC50 (48 h) was determined to be 1.35 mg/L (actual). The corresponding NOEC (48 h) was 1.37 mg/L (actual).
Executive summary:

The 48–hr-acute toxicity of LYSO toDaphnia Magnawas studied under semi- static conditions.  Test species were exposed to control and test chemical at nominal concentration of 100, 45.5, 20.7, 9.39, 4.27 mg/L for 48 hr.  Immobilisation and sublethal effects were observed daily.  The 48– hour EL50 was 46.3 mg/L (nominal).  The 48 – hr NOELR based on immobilization was 20.7 mg/L (nominal). 

 

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis

 

Test Organism Age (e.g. 1st instar): <24 hr

Test Type (Flowthrough, Static, Static Renewal): Semi-static

 

Summary of biological results

EL50 and NOELR-values of daphnids exposed to the test item evaluated using nominal loading rates

Endpoint

LYSO[mg/L]

 

24h

48 h

NOELR

100

20.7

EL50

> 100

46.3

95 % confidence limit of EL50

-

37.8 – 56.7

 

EC50 and NOEC-values of daphnids exposed to the test item evaluated using actual test item concentrations

Endpoint

LYSO[mg/L] (actual1))

 

24 h

48 h

NOEC

2.00

1.66

EC502)

> 2.00

1.66

95 % confidence limit of EC50

-

n.d.

Description of key information

The toxicity of LYSO was assessed in a 48-hr acute toxicity test with Daphnia magna according to OECD test guideline 202 and under GLP. According to the results of the test, the EL50(48 h) was determined to be 46.3 mg/L (nominal). The corresponding NOELR (48 h) was 20.7 mg/L (nominal).

Key value for chemical safety assessment

Additional information

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