1-(2,4-dichlorophenyl)ethan-1-one

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:

From 26 March 2018 to 28 March 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)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

HPLC - UV method.

Details on sampling:

- Concentrations: 6.25, 12.5, 25, 50 and 100 % saturated solutions.
- Sampling method: Samples were taken from the test solutions at the applied concentration levels and from the control solution at the beginning and at the end of the experiment.
- Sample storage conditions before analysis: not required.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Because the Test Item was not readily soluble in water by direct addition, a test solution was prepared using a saturated solution method. The solution was prepared by dispersing/dissolving 100 mg/L Test Item into the test medium (ISO Medium) two days before the start of the experiment. This solution was shaken for approximately 24 hours at approximately 30°C (Day - 2) and then was equilibrated for approximately 24 hours at approximately 20°C (Day - 1). Any non-dissolved test materials were removed by filtration through a fine (0.22 μm) filter to give the 100% saturated solution.
- Differential loading: nominal loading rate of 100 mg/L
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): no.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain: Daphnia magna
- Source: Szent István University, Department of Aquaculture, 2100 Gödöllő, Páter Károly ul. – Hungary.
- Age of the animals: less than 24 h old at the beginning of the test.
- Feeding during test: No

ACCLIMATION: There was no acclimatization because the water used was similar to the culture water.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

245 mg/L (as CaCO3)

Test temperature:

19.7 – 20.8ºC

pH:

7.26 – 7.85

Dissolved oxygen:

7.7 – 8.6 mg/L.

Nominal and measured concentrations:

Nominal concentrations: 0 (control), 6.25, 12.5, 25, 50 and 100 % saturated solutions.
Measured concentrations: 0, 3.54, 6.93, 15.5, 30.6 and 60.8 mg/L (geometric mean, measured)

Details on test conditions:

TEST SYSTEM
- Test vessel: Beaker
- Material, size, headspace, fill volume: glass beaker with a volume of 50 mL
- Aeration: No
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water (ISO medium, according to OECD 202)

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16-hour light and 8-hour dark cycle

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
The immobility or mortality of the Daphnia was determined by visual observation 24 and 48 hours after the start of the test. Those animals not able to swim within 15 seconds after gentle agitation of the test beaker are considered to be immobile.

RANGE-FINDING STUDY
A concentration range-finding test was conducted to determine the approximate toxicity of the test item so that appropriate test concentrations could be selected for use in the definitive test.
- Test concentrations: 0, 0.1, 1, 10 and 100 mg/L (10 daphnids per dose, semi-static, 48 hours)
- Results used to determine the conditions for the definitive study: Because toxic response was not observed during the preliminary concentration range-finding test, a limit test was carried out using only one test concentration (100 mg/L) and a control group in a semi-static system.

Reference substance (positive control):

yes

Remarks:

(Potassium dichromate is tested at least twice a year, last 06/07/2017)

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

7.94 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL: 6.84 – 9.90 mg/L

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

15.5 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

3.54 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

6.93 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

8.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL: 7.08 – 10.28 mg/L

Details on results:

- Behavioural abnormalities: No abnormal behaviour, appearance or any other effect on test animals were detected.
- Mortality of control: 0/20

Results with reference substance (positive control):

- Results with reference substance valid? Yes.
Potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.
The date of the last study (Study Code: 17/367-023DA) with reference item Potassium dichromate (batch no.: A0345704) is: 06/07/2017.
The 24h EC50: 0.65 mg/L, (95 % confidence limits: 0.61 – 0.70 mg/L)

Reported statistics and error estimates:

The 24h EC50 and 48 hours EC50 values were calculated using Probit analysis by SPSS/PC+ software. The 48h EC100 value of the Test Item was determined from the raw data. For the determination of the LOEC and NOEC, the immobilization at the test concentrations was tested on significant differences to the control values by Dunnett’s Test using TOXSTAT software.

Table 2. Summary of results.

Parameter (48 hours)	24 h EC50 (measured)	48 h EC50 (measured)	EC100 (measured)	NOEC (measured)	LOEC (measured)
	8.20 mg/L	7.94 mg/L	15.5 mg/L	3.54 mg/L	6.93 mg/L
95 % conf. limits	7.08 – 10.28 mg/L	6.84 – 9.90 mg/L	---	---	---

Table 3. Number and percentage of immobilised animals (definitive test).

Concentration		Number of treated animals	Immobilised animals
Nominal	Calc. geometric mean		24 hours		48 hours
(% saturated)	(mg/L)		number	%	number	%
Control	n.d.	20	0	0	0	0
6.25	3.54	20	0	0	0	0
12.5	6.93	20	5*	25	6*	30
25	15.5	20	20*	100	20*	100
50	30.6	20	20*	100	20*	100
100	60.8	20	20*	100	20*	100

*statistically significantly different compared to the control values (Dunnett’s Test; α = 0.05).

Validity criteria fulfilled:

yes

Remarks:

There was no immobilization in the control group and the dissolved oxygen concentration at the end of the test in control and test vessels was more than 3 mg/L.

Conclusions:

The test item has a 48h-EC50 = 7.94 mg/L (measured, 95% CL: 6.84-9.90 mg/L) and a 48h-NOEC = 3.54 mg/L, based on mobility.

Executive summary:

An acute immobilisation test on Daphnia magna was performed in accordance with OECD Guideline 202 and EU method C.2, following GLP. Twenty animals, divided into four groups of five animals each were exposed to the test item or the control for 48 h. Based on the results obtained in a preliminary range-finding test, the animals were exposed to 6.25, 12.5, 25, 50 and 100% saturated solutions of test item in a static system, since the test item was poorly soluble in water, and the saturated solutions were stable under test conditions. Test concentrations were analytically determined at the beginning and at the end of the test by an HPLC-UV method. As the deviation from the initial values was greater than 20% from the nominal, measured (geometric mean) concentrations are reported: 3.54, 6.93, 15.5, 30.6, and 60.8 mg/L. Positive controls (postassium dichromate) are performed at least twice a year to ensure the quality of the results. All validity criteria were met. The 48h-EC50 of the test item in daphnids was determined to be 7.94 mg/L (95% confidence limits: 6.84 – 9.90 mg/L) and the 48h-NOEC was determined to be 3.54 mg/L, both based on mobility.

Description of key information

Key study: Method according to OECD 202 and EU C.2. GLP study. The 48h-EC50 of the test item in Daphnia magna was found to 7.94 mg/L (measured, 95% CL: 6.84-9.90 mg/L) and the NOEC was 3.54 mg/L, both based on mobility.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

7.94 mg/L

Additional information

An acute immobilisation test in Daphnia magna was performed in accordance with OECD Guideline 202 and EU method C.2, following GLP. Twenty animals, divided into four groups of five animals each were exposed to the test item or the control for 48 h. Based on the results obtained in a preliminary range-finding test, the animals were exposed to 6.25, 12.5, 25, 50 and 100% saturated solutions of test item in a static system, corresponding to 3.54, 6.93, 15.5, 30.6, and 60.8 mg/L (measured, geometric mean). Test concentrations were analytically determined at the beginning and at the end of the test. Positive controls (postassium dichromate) are performed at least twice a year to ensure the quality of the results. All validity criteria were met. The 48h-EC50 of the test item in daphnids was determined to be 7.94 mg/L (95% confidence limits: 6.84 – 9.90 mg/L) and the 48h-NOEC was determined to be 3.54 mg/L, both based on mobility.