1-ethylazepan-2-one

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 Apr - 24 May 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

1992

GLP compliance:

yes

Analytical monitoring:

yes

Remarks:

UPLC

Details on sampling:

- Concentrations: Control and limit concentration at t = 0 h and t = 96 h
- Sampling method: 2.0 mL from the approximate centre of the test vessels
- Sample storage conditions before analysis: Samples were stored in a freezer (≤ -15 °C). Storage stability of the sampels was demonstrated in project 20144279.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution of 100 mg/L test item was prepared by application of 15 min magnetic stirring to accelerate dissolution in the test medium. Lower test concentrations were prepared by subsequent dilution of the highest concentration in test medium.
- Differential loading: No
- Controls: Test medium without test item.
- Evidence of undissolved material: All test solutions were clear and colorless at the end of the preparation procedure.

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM
- Common name: Carp
- Source: Zodiac, proefacc, "De Haar Vissen", Wageningen University and Research Centre, The Netherlands
- Age at study initiation: F1
- Length at study initiation: 2.4 ± 0.3 cm
- Weight at study initiation: 0.16 ± 0.09 g
- Growth stage and method of breeding: F1 from a single parent-pair bred in UV-treated water.

ACCLIMATION
- Acclimation period: At least 12 d after delivery
- Acclimation conditions: ISO medium with comparable water quality parameters, pH and temperature
- Health during acclimation: In the batch of fish used for the test, mortality during the 7 d prior to the start of the test was < 5%.

FEEDING
- Feeding during test: No feeding from 24 h prior test and during entire test.
- Feeding during holding: Daily feeding with pelleted fish food (Essence 300 - 500 µm, Coppens International bv, Helmond, The Netherlands)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

180 mg/L CaCO3 (ISO medium)

Test temperature:

Control: 20.7 - 21.1°C
Treatment: 20.7 - 21.1°C

pH:

Control: 7.7 - 8.0
Treatment: 7.5 - 8.0

Dissolved oxygen:

Control: 7.2 - 9.1 mg/L
Treatment: 6.0 - 9.1 mg/L

Nominal and measured concentrations:

Control and 100 mg/L (nominal)
Control and 82% of nominal (measured)

Details on test conditions:

TEST SYSTEM
- Test vessel: 6.5 L all-glass container filled with 5 L test solution
- Aeration: The test media were not aerated during the test.
- No. of organisms per vessel: 7 per test group
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 0.22 g fish/L (7 fish per 5 L of test medium)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Adjusted ISO medium prepared in tap water purified by Reverse Osmosis (RO-Water, GEON Waterbehandeling)
- Culture medium different from test medium: Culture medium same as test medium.
- Intervals of water quality measurement: Conductivity, pH, nitrite and ammonia concentration: once a week. Temperature: continuous. In addition, pH and temperature were measured before transferring the fish to the test system.

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16 h light, 8 h dark

EFFECT PARAMETERS MEASURED:
- Mortality and effects: At 2.75, 24, 48, 72 and 96 h. In addition, every afternoon vessels were checked for dead or severly distressed fish.
- Dissolved oxygen, pH and temperature: Daily in all vessels with surviving fish

TEST CONCENTRATIONS
- Range finding study : Yes,
- Test concentrations: 0.1 to 100 mg/L with a spacing factor of 10
- Results used to determine the conditions for the definitive study: Yes. No mortality or other clinical effects were observed at any of the test concentrations. The measured concentration at the start of the test was 83 mg/L and remained stable (i.e. 91 - 104% relative to initial). Therefore, the expected LC50 was above 83 mg/L.

Reference substance (positive control):

yes

Remarks:

Pentachlorophenol

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: No
- Mortality of control:0%
- Effect concentrations exceeding solubility of substance in test medium: No

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- LC50 (96 h) = 0.15 mg/L PCP (95% CI 0.1 - 0.22 mg/L)
- Other: The reference test was performed from 19 - 23 Mar according to OECD 203.

Reported statistics and error estimates:

No LC50 could be calculated because the test item was non-toxic (LC50 > maximum concentration).

Sublethal observations / clinical signs:

VALIDITY CRITERIA

The study fulfilled the validity criteria defined by the OECD guideline and is thus considered reliable and valid.

 

Table 1: Validity criteria for OECD 203.

Criterion from the guideline	Outcome	Validity criterion fulfilled
The mortality in the control(s) should not exceed 10% (or one fish if less than ten are used) at the end of the test	Mortality in the control was 0%.	Yes
The dissolved oxygen concentration must have been at least 60 per cent of the air saturation value throughout the test	The dissolved oxygen concentration was ≥ 60% of the air saturation throughout the test (> 5 mg/L at 22 °C).	Yes
There must be evidence that the concentration of the substance being tested has been satisfactorily maintained, and preferably it should be at least 80 per cent of the nominal concentration throughout the test. If the deviation from the nominal concentration is greater than 20 per cent, results should be based on the measured concentration.	The measured test item concentrations were at least 80% of nominal throughout the test.	Yes

 

 ANALYTICAL RESULTS

The measured concentration in the limit concentration was 82% of nominal at the beginning and end of the test. Based on this result, the effect parameters were expressed in terms of the analytically confirmed nominal concentration.

 

BIOLOGICAL RESULTS

After 96 h, no mortality or other clinical effects were observed at the limit concentration throughout the test, resulting in an LC50 (96 h) > 100 mg/L (nominal).

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Description of key information

Not acutely toxic to fish. LC50 (96 h) >100 mg/L (nominal).

Additional information

The acute toxicity of N-ethylcaprolactam to fish was determined in a study according to OECD 203. Fish of the species Cyprinus carpio were exposed to a test substance concentration of 100 mg/L in a static limit test. The test substance concentration was analytically verified via Ultra Performance Liquid Chromatography (UPLC). The recovery rate was 82% of the nominal test concentration. Thus, the effect concentration was based on the nominal test concentration. No mortalities or symptoms of intoxication were observed during the 96 h test period. The determined LC50 (96 h) was >100 mg/L (nominal).
Based on the results of the acute toxicity testing N-ethylcaprolactam is considered not acutely toxic to fish.