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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:

2020-02-04 to 2020-02-14

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:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.0 (NC) and 200 mg/L (A)
- Sampling method: After 0, 24 (before and after renewal of test solutions), and 48 h exposure samples were taken from the test solutions: 2 samples of 2 mL per treatment group. The samples were filled from the test vessels directly into 8 mL glass vials without any additional treatment.
- Sample storage conditions before analysis: To each vial, 2 mL acetonitrile was added and samples were stored in the freezer (≤ -18 °C).

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The stock solution was prepared by adding 100.1 mg test item to 500 mL test medium, sonicating (until no larger particles are visible) and shaking for 48 h using an overhead shaker at 22.7–24.4 °C.
- Controls: yes
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): The filtered stock solution was visually clear, without particles.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Age at study initiation (mean and range, SD): 1.5–20.5 h
- Stage and instar at study initiation: 1st instar
- Method of breeding: The daphnids are cultured at approx. 20 °C with 16 h light : 8 h dark and placed into fresh Elendt M4 medium twice a week. They were kept at approx. 10 animals/200 mL and fed on workdays with Desmodesmus subspicatus algae corresponding to 0.1 mg C × daphnid-1 × day-1.
- Source: Originates from the clone breeding of the Federal Environment Agency, department IV 2.4, Berlin, and has been cultivated at Hydrotox GmbH since October 2012.
- Feeding during test: No

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test temperature:

20.1–21.2 °C

pH:

7.8–7.9

Dissolved oxygen:

8.2–8.8 mg/L (control)

Nominal and measured concentrations:

0 and 200 mg/L (nominal)
measured: 0.19–0.69 % of the nominal loading rate

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers
- Type (delete if not applicable): open
- Volume of solution: 40 mL
- Aeration: No
- Renewal rate of test solution (frequency/flow rate): Yes, after 24 h
- No. of organisms per vessel: 4
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
The test was performed with Elendt M4 medium according to OECD 202 (2004).

OTHER TEST CONDITIONS
- Adjustment of pH: yes, adjustment to 8.2/8.1 of the stock solution
- Photoperiod: 16 h light : 8 h dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Mobility/mortality:
The swimming capability of the daphnids was determined after 24 h and 48 h exposure. Animals that did not swim within 15 s after gently moving the test vessel were considered to be immobile.

RANGE-FINDING STUDY
- Test concentrations: 8, 40 and 200 mg/L
- Results used to determine the conditions for the definitive study: Yes, no effect measured

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

> 0.768 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.768 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: No
- Other biological observations: No
- Mortality of control: No
- Other adverse effects control: No
- Immobilisation of control: No
- Abnormal responses: No
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No
- Effect concentrations exceeding solubility of substance in test medium: No

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50 = 0.6–2.1 mg/L, according to OECD guideline 202
- Limit test: No
- Dose-response test: Yes
- ECx: 1.95 mg/L
- Other: None

Reported statistics and error estimates:

As no effect on the test organisms was observed, no statistical data evaluation was performed.

Table 1: Immobility after 24 h and 48 h exposure

Nominal test item loading rate [mg/L]	Daphnia introduced				Immobile daphnia (replicates 1 – 4)								Immobility [%]
	0 h				24 h				48 h				24 h	48 h
	1	2	3	4	1	2	3	4	1	2	3	4
NC	5	5	5	5	0	0	0	0	0	0	0	0	0	0
200	5	5	5	5	0	0	0	0	0	0	0	0	0	0

Table 2: Analytically measured test item concentrations after 0 h, 24 h (before and after renewal) and 48 h exposure

Nominal test item loading rate [mg/L]	Sample	Sampling time    [h]	Calculated test item  concentration     [mg/L]	Recovery [%] nominal	Time-weighted mean test item concentration [mg/L]
NC	1502-NC1-0h	0	No Peak	--	--
	1502-NC1-24hOld	24 Old	No Peak	--
	1502-NC1-24hNew	24 New	No Peak	--
	1502-NC1-48h	48	No Peak	--
200 *	1502-A1-0h	0	0.656	0.33	0.768
	1502-A1-24hOld	24 Old	0.383	0.19
	1502-A1-24hNew	24 New	1.37	0.69
	1502-A1-48h	48	0.748	0.37

LOD: 0.008 mg/L

LOQ: 0.025 mg/L

* Apart from slight differences in the temperature during the 48 h shaking period (0.3 °C difference) and the pH after 24 h shaking (0.1 pH units difference), which are most likely negligible, there is no cause in the experimental frame conditions obvious which could explain the clear difference between the test item concentration in the test item solution at 0 h and the new test item solution at 24 h.

Criteria of validity:

- Immobilisation of the test organisms in the control at the end of the test was 0 % and therefore ≤ 10 %. 

- Dissolved oxygen concentration in the control and the test item treatments at the end of the test was ≥ 8.2 mg/L and therefore ≥ 3 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

No obvious effect on appearance and behaviour of the daphnids in the control and the test item treatment was observed until the end of the exposure period.

Executive summary:

The 48-h acute toxicity of N-(4-((4-(3-phenylureido)phenyl)sulfonyl)phenyl)benzenesulfonamide to Daphnia magna was studied under semi-static conditions as described in the OECD Guideline no. 202 (cf. limit test) and according to the OECD principles of Good Laboratory Practice.

Test organisms were exposed to a control, and the test item at a nominal concentration of 200 mg/L for 48 hours. Immobilisation and sublethal effects were observed daily.

The test substance appeared to be completely dissolved at the concentration tested (visually assessed). Test substance concentrations were analytically monitored.

As the measured test item concentrations were not within ± 20 % of the nominal concentrations, all results are given in relation to the analytically measured test item concentrations, as required by OECD guideline 201 (2004) and OECD series on testing and assessment no. 23 (2000).

Based on the results of this study, the test item would not be classified as toxic to Daphnia magna in accordance with the classification system of the CLP Regulation (EC) No 1272/2008.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Results synopsis

Test organism age (e.g. 1st instar): 0.5–20.25 h

Test type: Semi-static, renewal

48 hr LOEC: > 0.786 mg/L

48 hr NOEC: ≥ 0.786 mg/L

Endpoint(s) effected: Mobility

Description of key information

The test item had no effect on the mobility of daphnids at maximum water solubility (nominal loading: 200 mg/L; mean measured concentration:; 0.768 mg/L).

LOEC > 0.768 mg/L

NOEC ≥ 0.768 mg/L

Additional information

A limit test with nominal concentration of 200 mg/L was performed according to OECD 202 and under GLP. No obvious effect on appearance and behaviour of the daphnids in the control and the test item treatment was observed until the end of the exposure period. A semi-static test design was applied with renewal of test solutions after 24 h and an accompanying substance-specific chemical analysis to determine the test item concentrations in the test vessels. The swimming capability of the daphnids was assessed after 24 h and 48 h exposure. As the measured test item concentrations are not within ± 20 % of the nominal loading rate, according to OECD 202 (2004), all results are given in relation to the measured test item concentrations (time-weighted mean).

Summary of results:

LOEC > 0.768 mg/L

NOEC ≥ 0.768 mg/L