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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 ****
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 (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
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.
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.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
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
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. The No Observed Effect Loading rate (NOEL) was 100 mg/L loading rate WAF.
Executive summary:

A study was performed to assess the acute toxicity of the test material toDaphnia magna. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (April 2004) No 202, "Daphniasp., Acute Immobilisation Test", and Method C.2 of Commission Regulation (EC) No. 440/2008. 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.  The No Observed Effect Loading rate (NOEL) was 100 mg/L loading rate WAF.

Description of key information

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.  The No Observed Effect Loading rate (NOEL) was 100 mg/L loading rate WAF.

Key value for chemical safety assessment

Additional information