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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
30Oct2018 to 28Feb2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report Date:
2019

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Details on test material:
Batch 1075126
Specific details on test material used for the study:
Identification: 2-[(4-aminophenyl)azo]-1,3-dimethyl-1Himidazolium chloride
Batch (Lot) Number: 1075126
Expiry date: 24 July 2022 (expiry date)

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Samples for possible analysis were taken from the stock solution, all test concentrations and the control according to the schedule below.

Frequency at t=0 h and t=48 h
Volume 1.8 mL from the approximate centre of the test vessels
Storage Samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the Test Facility.
At the end of the exposure period, the replicates were pooled at each concentration before sampling.

Additionally, reserve samples of 1.8 mL were taken for possible analysis. If not used, these samples were stored in a freezer (≤-15°C) for a maximum of three months after delivery of the draft report, pending on the decision of the sponsor for additional analysis.

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
Species Daphnia magna (Crustacea, Cladocera) (Straus, 1820), at least third generation, obtained by a cyclical parthenogenesis under specified breeding conditions.

Source In-house laboratory culture with a known history.

Reason for selection This system has been selected as an internationally accepted invertebrate species.

Validity of batch Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20%1, presence of males, ephippia or discoloured animals and there was no delay in the production of the first brood.

Characteristics Daphnia, less than 24 hours old, from parental daphnids of more than two weeks old.

Study design

Test type:
static
Water media type:
other: M7, as prescribed by Dr. Elendt-Schneider (Elendt, B.-P., 1990: Selenium deficiency in Crustacea. An ultrastructural approach to antennal damage in Daphnia magna Straus. Protoplasma 154, 25-33).
Limit test:
yes
Total exposure duration:
48 h
Remarks on exposure duration:
In alignment with OECD 202
Post exposure observation period:
N/A

Test conditions

Hardness:
The hardness of test medium expressed as CaCO3: 180 mg/L
pH:
8.0 to 8.2 throughout duration of the test.
Dissolved oxygen:
9.2-9.7 mg/L throughout duration of the test.
Salinity:
N/A
Nominal and measured concentrations:
Limit/Range test
0.1; 0.117-0.124
1.0; not analysed
10; 10.8-11.3
100; not tested

Final test
Nominal (mg/L); Measured (mg/L)
0.46;0.443-0.453
1.0; 0.986-1.01
2.2; 2.25-2.32
4.6; 4.50-4.52
10; 9.97-10.3
Details on test conditions:
Test duration; 48 hours
Test type; Static
Test vessels; 60 mL, all-glass.

Test medium; The following salts (analytical grade) were added to tap water purified by Reverse Osmosis (RO-water, GEON Waterbehandeling, Berkel-Enschot, The Netherlands):
CaCl2.2H2O 211.5 mg/L
MgSO4.7H2O 88.8 mg/L
NaHCO3 46.7 mg/L
KCl 4.2 mg/L
The hardness of test medium expressed as CaCO3: 180 mg/L with a pH between 6 and 9.

Number of daphnids; 20 per concentration
Loading; 5 per vessel containing 50 mL of test solution.
Light; A daily photoperiod of 16 hours.
Feeding; No feeding
Aeration; No aeration of the test solutions was applied.
Introduction of daphnids; 41 minutes after preparation of the test solutions.
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
4.3 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
3.2 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Reported statistics and error estimates:
The 48h-EC50 for Daphnia magna exposed to 2-[(4-aminophenyl)azo]-1,3-dimethyl-1H-imidazolium chloride was 3.2 mg/L based on analytically confirmed nominal concentrations (95% confidence interval between 2.2 and 4.6 mg/L).

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In conclusion, the 48h-EC50 for Daphnia magna exposed to 2-[(4-aminophenyl)azo]-1,3- dimethyl-1H-imidazolium chloride was 3.2 mg/L based on analytically confirmed nominal concentrations (95% confidence interval between 2.2 and 4.6 mg/L).
Executive summary:

The objective of the study was to evaluate 2-[(4-aminophenyl)azo]-1,3-dimethyl-1Himidazolium chloride for its ability to generate acute toxic effects on the mobility of Daphnia magna during an exposure period of 48 hours and, if possible, to determine the EC50 at 24 and 48 hours of exposure.

The study procedures described in this report were based on the OECD guideline No. 202, 2004.

The batch of 2-[(4-aminophenyl)azo]-1,3-dimethyl-1H-imidazolium chloride tested was a brown powder with a purity of 99.85% and completely soluble in test medium at the concentrations tested.

A final test was performed based on the results of a preceding combined limit/range-finding test. Twenty daphnids per group (5 per replicate, quadruplicate) were exposed to an untreated control and to nominal concentrations of 0.46, 1.0, 2.2, 4.6 and 10 mg/L. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test.

Samples taken from all test concentrations and the control were analysed. The measured concentrations were at the level of the nominal concentrations throughout the exposure period, i.e. at 96-106% relative to the nominal concentrations at the start and at the end of the test. The effect parameters were thus based on analytically confirmed nominal concentrations.

No immobility was observed in the control and the three lowest test concentrations throughout the exposure period, while 55% of daphnids exposed to 4.6 and 10 mg/L were immobilized at 24 hours of exposure and 100% of daphnids exposed to 4.6 and 10 mg/L were immobilized at the end of the test.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

In conclusion, the 48h-EC50 for Daphnia magna exposed to 2-[(4-aminophenyl)azo]-1,3 -dimethyl-1H-imidazolium chloride was 3.2 mg/L based on analytically confirmed nominal concentrations (95% confidence interval between 2.2 and 4.6 mg/L).