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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:
14 July 2017 to 03 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)
Version / remarks:
April 2004
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to a Water Accommodated Fraction (WAF) of the test material at a nominal loading rate of 100 mg/L for 48 hours at a temperature of 21°C to 22°C under static test conditions. Immobilization and any adverse reactions to exposure were recorded after 24 and 48 hours.

- Sample storage conditions before analysis: The samples were stored frozen prior to analysis. Given that concentrations close to the limit of quantification (LOQ) were observed in the preliminary work, when samples were analysed promptly following collection, it was considered unnecessary to conduct any storage stability analysis.
Vehicle:
no
Details on test solutions:
A nominal amount of test material (500 mg) was added to the surface of 5 liters of test water to give the 100 mg/L loading rate. After the addition of the test material, the test water was stirred by magnetic stirrer using a stirring rate such that a vortex was formed to give a dimple at the water surface. The stirring was stopped after 95 hours and the mixture allowed to stand for 1 hour.
Test organisms (species):
Daphnia magna
Details on test organisms:
Daphnia magna is a freshwater invertebrate representative of a wide variety of natural habitats, and can therefore be considered as an important non-target organism in freshwater ecosystems.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Post exposure observation period:
Any immobilization or adverse reactions to exposure were recorded at 24 and 48 hours after the start of exposure.
Test temperature:
18 to 22 °C with a maximum deviation of ±1 °C
pH:
pH ranged from 7.6 to 7.7
Dissolved oxygen:
range from 8.5 to 8.7 mg O2/L throughout the test
Nominal and measured concentrations:
Nominal loading rates of 1.0, 10 and 100 mg/L.
Details on test conditions:
TEST SYSTEM
- Test vessel:150 mL glass beakers
- Type (delete if not applicable):closed
- Material, size, headspace, fill volume: 150 mL glass beakers
- Volume of solution: 100 mL Elendt M7 medium
- Aeration: the test vessels were not aerated
- Renewal rate of test solution (frequency/flow rate): The test preparations were not renewed during the exposure period.
- No. of organisms per vessel: five daphnids/ vessels
- No. of vessels per concentration (replicates): four replicate
- No. of vessels per control (replicates): four replicate
- No. of vessels per vehicle control (replicates): none


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water (Elendt M7) used for both the range-finding and definitive tests. The pH of the prepared media was 7.9 ± 0.3.
- Culture medium different from test medium: no
- Intervals of water quality measurement: every 24 hours

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: photoperiod of 16 hours light (between 200 and 1200 lux) and 8 hours darkness with 20 minute dawn and dusk transition periods.
- Light intensity: Throughout the test the light intensity was observed to be in the range 772 to 870 lux.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Any immobilization or adverse reactions to exposure were recorded at 24 and 48 hours after the start of exposure.

VEHICLE CONTROL PERFORMED: no

RANGE-FINDING STUDY
- Test concentrations: In the range-finding test Daphnia magna were exposed to a series of nominal loading rates of 1.0, 10 and 100 mg/L.
- Results used to determine the conditions for the definitive study: No immobilization was observed at 1.0, 10 and 100 mg/L loading rate WAF. Based on this information, a single loading rate of four replicates, of 100 mg/L, was selected for the definitive test.
Reference substance (positive control):
yes
Remarks:
A positive control (Envigo Study Number XT01HS) using potassium dichromate as the reference item was conducted between 20 October 2016 and 22 October 2016 (at concentrations of 0.32, 0.56, 1.0, 1.8 and 3.2 mg/L). The result were within the normal range.
Key result
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Key result
Duration:
48 h
Dose descriptor:
LOELR
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Details on results:
No immobilization was observed at 1.0, 10 and 100 mg/L loading rate WAF.
Sub-lethal effects of exposure were observed in the 100 mg/L loading rate test concentration. This response was a single daphnia being small in size (see Table 1). As less than 10% of the daphnia in this concentration were affected, this was considered to be due to natural causes and as such considered not to have had an impact on the outcome of the test.
Based on this information, a single loading rate of four replicates, of 100 mg/L, was selected for the definitive test. This experimental design conforms to a "Limit test" to confirm that no immobilization or adverse reactions to exposure were observed.
Chemical analysis of the test preparations at 0 and 48 hours showed measured test concentrations of less than the limit of quantification (LOQ) of the analytical method employed, which was determined to be 0.066 mg/L, were obtained. This does not infer that no test item was in solution, just that the measured dissolved test item was present at a concentration of less than the LOQ and may have comprised one or several components of the test item.
Measured concentrations obtained were found to be significantly lower than those obtained during the preliminary media preparation trial. This was considered to be due to the media used for testing affecting the solubility of the test item.
Results with reference substance (positive control):
The results from the positive control with potassium dichromate were within the normal range for this reference item.
Reported statistics and error estimates:
An estimate of the loading rate causing 50% immobilization in the treatment group (EL50) was given by inspection of the immobilization data.
Validity criteria fulfilled:
yes
Remarks:
The test was considered to be valid given that no more than 10% of the control daphnids showed immobilization or other signs of disease and the oxygen concentration at the end of the test was equal to or greater than 3 mg/L in the control and test vessels
Conclusions:
The acute toxicity of the test material to the freshwater invertebrate Daphnia magna was investigated and the 48-hour EL50 value was determined to be greater than 100 mg/L loading rate WAF.
Executive summary:

A study following GLP was performed to assess the acute toxicity of the test item (EC =953-378-2), 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", and Method C.2 of Commission Regulation (EC) No. 440/2008.

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, twenty daphnids (4 replicates of 5 animals) were exposed to a Water Accommodated Fraction (WAF) of the test item at a nominal loading rate of 100 mg/L for 48 hours at a temperature of 21 °C to 22 °C under static test conditions. Immobilization and any adverse reactions to exposure were recorded after 24 and 48 hours.

Chemical analysis of the test preparations at 0 and 48 hours showed measured test concentrations of less than the limit of quantification (LOQ) of the analytical method employed were obtained which was determined to be 0.066 mg/L. This does not indicate that no test item was in solution, just that the measured dissolved test item was present at a concentration of less than the LOQ. Any dissolved test item may have been comprised of 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 resulted in EL50 values of greater than 100 mg/L loading rate WAF. The No Observed Effect Loading Rate was 100 mg/L loading rate WAF.


 

Description of key information

An experimental study was carried out to determine the aquatic toxicity of the registered substance on freshwater invertebrate Daphnia magna according to the TG OECD 202 and GLP. The acute toxicity was investigated and the 48-hour EL50 value was determined to be greater than 100 mg/L loading rate WAF.  

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Dose descriptor:
EC50
Remarks:
EL50 : loading rate (WAF)
Effect concentration:
> 100 mg/L

Additional information

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