[No public or meaningful name is available]

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:

Experimental Phase:15 Janaury 2018 to 30 March 2018. Report Issue: 09 October 2018.

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:

yes

Remarks:

A correction to the test substance chemical name was made during the study along with an amendment to the name of the Study Monitor. These changes were not considered to have any impact on the conclusions of the study.

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

yes

Remarks:

A correction to the test substance chemical name was made during the study along with an amendment to the name of the Study Monitor. These changes were not considered to have any impact on the conclusions of the study.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples were taken from the control and each test group from the bulk test preparation at 0 hours and from the pooled replicates at 48 hours for quantitative analysis. Samples were stored frozen prior to analysis. Duplicate samples were taken and stored frozen for further analysis if necessary.

Only samples at the NOEL rate and above were analysed.

Vehicle:

no

Details on test solutions:

Due to the low aqueous solubility and complex nature of the test item, for the purposes of the study the test medium was prepared as a Water accommodated Fraction (WAF) of the test item.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea (Daphnia magna)
- Source: first instar Daphnia magna derived from in-house laboratory cultures.
- Feeding during test: None during exposure to test susbtance.
- Food type: Mixture of algal suspension (Desmodesmus subspicatus) and Tetramin® flake food suspension.
- Frequency: Daily

ACCLIMATION
- Acclimation period: None

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:

Adult daphnids were maintained in 150 mL glass beakers containing 100 mL Elendt M7 medium in a temperature controlled room maintaining the water temperature at 18 to 22 °C. The lighting cycle was controlled to give a 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods. Culture conditions ensured that reproduction was by parthenogenesis. Gravid adults were isolated the day before initiation of the test, such that the young daphnids produced overnight were less than 24 hours old. These young were removed from the cultures and used for testing. The diet and diluent water are considered not to contain any contaminant that would affect the integrity or outcome of the study.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

21 to 22 ºC.

pH:

The pH test media ranged from 7.8 to 7.9.

Dissolved oxygen:

8.3 to 9.1 mg O2/L

Nominal and measured concentrations:

Chemical analysis of the 1.25 and 2.5 mg/L loading rate fresh test preparations at 0 hours showed measured test concentrations of 0.17 and 0.66 mg/L were obtained respectively. Chemical analysis of the aged test preparations at 48 hours showed measured test concentrations of 0.016 and 0.10 mg/L were obtained respectively.

The dissolved test item may have been one or several components of the test item. Given that the toxicity cannot be attributed to a single component or a mixture of components, but to the test item as a whole, the results were based on nominal loading rates only.

Details on test conditions:

TEST SYSTEM - MAIN TEST
- Test vessel: 150 mL glass beakers
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: 100 mL Elendt M7 Medium
- Aeration: No
- No. of organisms per vessel: Five
- No. of vessels per concentration (replicates): Four
- No. of vessels per control (replicates): Four


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water (Elendt M7) prepared in-house.


OTHER TEST CONDITIONS
- pH: The pH of the prepared media was 7.9 ±0.3
- Photoperiod: 16 hours light and 8 hours darkness with 20 minute dawn and dusk transition periods
- Light intensity: 200 to 1200 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

VEHICLE CONTROL PERFORMED: No (no vehicle)

RANGE-FINDING STUDY
- Test concentrations: Nominal loading rates of 1.0, 10 and 100 mg/L.
- Results used to determine the conditions for the definitive study: Yes

MAIN STUDY
- Test concentrations: Based on the results of the range-finding test, the following loading rates were assigned to the definitive test: 0.16, 0.32, 0.63, 1.25 and 2.5 mg/L.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (run as a separate study)

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

1.5 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Water Accommodated Fraction

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

125 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Water Accommodated Fraction

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

LOELR

Effect conc.:

2.5 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Water Accommodated Fraction

Basis for effect:

mobility

Details on results:

No sub-lethal effects from exposure were observed during the test.

Results with reference substance (positive control):

The results from the positive control (run as a separate study) with potassium dichromate were within the normal historical range for the laboratory.

Reported statistics and error estimates:

The EL50 values at 24 and 48 hours and the slope of the response curve and its standard error were calculated by Probit analysis using Linear Maximum-Likelihood regression. The Lowest Observed Effect Loading (LOEL) rate and the No Observed Effect Loading Rate (NOEL) rate at 24 and 48 hours were calculated using the Step-down Cochran Armitage Test Procedure. All results were calculated using the ToxRat Professional computer software package (TOXRAT).

Validity criteria fulfilled:

yes

Conclusions:

Based on the water accommodated fraction (WAF) the test substance 48-hour EL50 (mg/L loading rate WAF) was 1.5 mg/L. The No Observed Effect Level (NOEL) was 1.25 mg/L and the Lowest Observed Effect Level (LOEL) was 2.5 mg/L.

Executive summary:

Introduction

A study was performed to assess the acute toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No 202, "Daphnia sp., Acute Immobilisation Test" referenced as Method C.2 of Commission Regulation (EC) No. 440/2008.

 

Methods

Due to the low aqueous solubility and complex nature of the test item, for the purposes of the test, the test medium was prepared as a Water Accommodated Fraction (WAF).

 

Following a preliminary range-finding test and initial experiments, 20 daphnids (4 replicates of 5 animals) were exposed to Water Accommodated Fractions (WAFs) of the test item over a range of nominal loading rates of 0.16, 0.32, 0.63, 1.25 and 2.5 mg/L for 48 hours at a temperature of 20 °C to 22 °C under static test conditions. The number of immobilised daphnia and any adverse reactions to exposure were recorded after 24 and 48 hours.

 

Results

Chemical analysis of the 1.25 and 2.5 mg/L loading rate fresh test preparations at 0 hours showed measured test concentrations of 0.17 and 0.66 mg/L were obtained respectively. Chemical analysis of the aged test preparations at 48 hours showed measured test concentrations of 0.016 and 0.10 mg/L were obtained respectively.

 

The dissolved test item may have been one or several components of the test item. Given that the toxicity cannot be attributed to a single component or a mixture of components, but to the test item as a whole, the results were based on nominal loading rates only.

 

Exposure of Daphnia magna to the test item gave the following results:

Time Point (Hours)	EL50 (mg/L Loading Rate WAF)	95% Confidence Limits (mg/L Loading Rate WAF)	NOEL (mg/L)	LOEL (mg/L)
48	1.5	Not determined due to the nature of the data	1.25	2.5

 

 

Conclusion

Based on the water accommodated fraction (WAF) the test substance 48-hour EL50 (mg/L loading rate WAF) was 1.5 mg/L. The No Observed Effect Level (NOEL) was 1.25 mg/L and the Lowest Observed Effect Level (LOEL) was 2.5 mg/L.

Description of key information

Acute toxicity of the test substance to Daphnia magna.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1.5 mg/L

Additional information

Based on the water accommodated fraction (WAF) the test substance 48-hour EL50 (mg/L loading rate WAF) was 1.5 mg/L. The No Observed Effect Level (NOEL) was 1.25 mg/L and the Lowest Observed Effect Level (LOEL) was 2.5 mg/L.