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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:
September - November 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:
2004
GLP compliance:
yes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: Batch number 170808-29
- Expiration date of the lot/batch: 28/Aug/2019
- Purity test date: 99.71 % w/w
Analytical monitoring:
yes
Details on sampling:
At the beginning and at the end of the test, aliquots of the test solutions were taken for determining the test substance active ingredient concentration. The test substance concentration in the solutions was determined by analyzing for the active ingredient (Benzyl glycol)
Vehicle:
no
Details on test solutions:
The primary stock solution used in the range-finding test was prepared by dissolving 10.0 mg of the test substance in 40 mL of dilution water — M4 and the total volume was completed to 100 mL, resulting in a concentration of 100 mg.L-1.
The secondary stock solutions were prepared by dilutions of the primary stock solution.
The primary stock solution used in the definitive test was prepared by dissolving 20.0 mg of the test substance in 40 mL of dilution water — M4 and the total volume was completed to 200 mL, resulting in a concentration of 100 mg.L-1.
The test solutions were prepared from dilutions of the stock solutions.

- Method: Starting from the 100 mg/L SOLUTION in ISO test water, following test solutions in ISO test water were prepared: 1, 1.6, 2.5, 4, 6.3, 10 mg/L.
100 mg/L SOLUTION in ISO test water was prepared new for each test
- Eluate: NO
- Controls: ISO TEST SOLUTION without test substance
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): NO
Test organisms (species):
Daphnia magna
Details on test organisms:
The test system used for this study is described below, according to Straus (1820):
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Branchiopoda
Order: Cladocera
Family: Daphniidae
Genus: Daphnia
Species: Daphnia magna
Young Daphnia magna <= 24 hours old were obtained from the culture kept at the Ecotoxicology Laboratory, maintenance and cultivation records are archived at BIOAGRI.

The test system Daphnia magna was obtained from the CAROLINA BIOLOGICAL SUPPLY COMPANY - Burlington, North Carolina (USA) and maintained as a stock culture at BIOAGRI.
Nearly 24 hours before the Acute Toxicity Test started, Daphnia with eggs were isolated in crystallizing dishes and fed with algae suspension. In the following morning, the
Test type:
semi-static
Water media type:
freshwater
Total exposure duration:
48 h
Hardness:
179.1 to 185.2 mg/L of CaCO3
Test temperature:
20±2°C - 20±3°C
pH:
7.7÷7.8
Dissolved oxygen:
8.0-8.1 mg/L
Nominal and measured concentrations:
Nominal concentration (mg.L-1):100
Average effective concentrations (mg.L-1): 105.0215 5.02
Details on test conditions:
In the range-finding test the exposure conditions were:
a) Total number of organisms per each tested concentration or control: 10;
b) Number of replicates per each tested concentration and control: 2;
c) Number of organisms per test container: 5;
d) Volume: 15 mL of test solution per test container, 3 mL to each Daphnia;
e) The organisms were distributed randomly in the test container. Firstly, three organisms were placed in each test container and, finally, two organisms were added to the container;
f) Nominal used concentrations: control; 0.1; 1; 10 and 100 mg.L-1;
g) Temperature of the test solutions: 20.1 to 20.2°C;
h) Photoperiod: in the dark;
i) Parameters evaluated: immobility after 24 and 48 hours; and still animals were considered unable to swim for a period of 15 seconds of observation after mild agitation of the flasks.

In the definitive test the exposure conditions were:
a) Total number of organisms per each tested concentration or control: 20;
b) Number of replicates per each tested concentration and control: 4;
c) Number of organisms per test container: 5;
d) Volume: 15 mL of test solution per test container, 3 mL to each Daphnia;
e) The organisms were distributed randomly in the test container. Firstly, three organisms were placed in each test container and, finally, two organisms were added to the container;
f) Nominal used concentrations: control and 100 mg.L-1;
g) Temperature of the test solutions: 20.1 to 20.3°C;
h) Photoperiod: in the dark;
i) Parameters evaluated: immobility after 24 and 48 hours; and still animals were considered unable to swim for a period of 15 seconds of observation after mild agitation of the flasks;
j) Analytical determination: content dissolved oxygen, pH of the test solutions and the test substance concentration were determined at the beginning of the test and after 48 hours.
Reference substance (positive control):
yes
Remarks:
Potassium Dichromate
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
>= 100 mg/L
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
The 48-hours E050 value was not determined because the highest tested concentration of 2-(Benzyloxy) ethanol, 100 mg.L-1, did not cause immobility to the test organisms. Therefore the 48-hours E050 value of the tested substance is higher than 100 mg/L.

The 24-hours EC50 value of the reference substance (potassium dichromate) was 0.92 mg.L-1 (95% confidence limits = 0.80 to 1.06 mg1-1), showing the sensitivity of the test system (ISO 6341 / OECD 202, 2004).

The values of pH of the control and test solutions measured at 0 and 48 hours not deviate more than 1.5 units during the test.
Reported statistics and error estimates:
The 24-hours EC50 value of the reference substance and their respective 95% confidence limits were determined by using the statistical Trimmed Spearman-Karber Method (HAMILTON et a/.,1977).
Validity criteria fulfilled:
yes
Conclusions:
The 48-hours EC50 value was not determined because the highest tested concentration of 2- (Benzyloxy) ethanol, 100 mg/, did not cause immobility to the test organisms. Therefore the 48-hours EC50 value ofthe tested substance is higher than 100 mg./L.

Description of key information

Key value for chemical safety assessment

Additional information

The 48-hours EC50 value was not determined because the highest tested concentration of 2 -(Benzyloxy) ethanol, 100 mg/L did not cause immobility to the test organisms. Therefore the 48-hours EC50 value ofthe tested substance is higher than 100 mg/L