4'-methoxyacetophenone

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:

2017-04-24 to 2017-06-07

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Duplicate samples taken from each test concentration and the control at the start and at the end of the test (after 48 hours)
- For 48-h stability samples: contents of the respective replicates were combined prior to sampling
- samples frozen at about -20 °C immediately after sampling

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The highest nominal stock solution of 100 mg/L was prepared with test water just prior to application using ultrasonic treatment for
15 minutes and intense stirring for 15 minutes at room temperature.
- Stock solution: 100 mg/L, prepared with test water just prior to application
- Test media were prepared just before the introduction of the daphnids (i.e., the start of the exposure)
- Controls: Test water without test item tested under the same conditions as the test groups

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain/clone: Straus
- Source: Daphnia Collection of the University of Basel/Switzerland in 2015
- Age of parental stock: 6-24 hours old, not first brood progeny
- Feeding during test: no

ACCLIMATION
- Cultivation of the parental daphnids was performed in reconstituted water of the quality identical to the water quality used in the tests (with respect to pH, main ions, and total hardness)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

Not applicable

Hardness:

250 mg/L CaCO3 (2.5 mmol/L)

Test temperature:

between 20 and 21 °C

pH:

- Control: 7.8 - 7.9
- Test item: 7.8 - 7.9

Dissolved oxygen:

- Control: 8.5 mg/L
- Test item: 8.5 - 8.7

Salinity:

Not measured

Conductivity:

Not measured

Nominal and measured concentrations:

Nominal: control, 6.25, 12.5, 25, 50 and 100 mg/L
Measured (0 h fresh): < LOQ, n.a., n.a., 25.9, 51.4 and 102 mg/L
Measured (48 h aged): < LOQ, n.a., n.a., 25.2, 50.0 and 99.3 mg/L
n.a. = not analyzed, since these concentrations were below the NOEC determined in this test and thus not relevant for the interpretation of the biological results

Details on test conditions:

TEST SYSTEM
- Test vessel: 100-mL glass beakers
- Type: covered with glass plates
- Fill volume: 50 mL
- Application: Once within 48 h
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Reconstituted test water (ISO Test water) according to OECD Guideline No. 202
- Aeration prior the test: yes, until oxygen saturation was reached
- Aeration during the test: no
- Temperature: maintained between 20 and 21 °C

OTHER TEST CONDITIONS
- Photoperiod: 16-hour light to 8-hour dark cycle with a 30-minute transition period
- Light intensity: 15 and 17 μmol m-2 s-1

TEST CONCENTRATIONS
- Range finding study
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

75 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: See following table
- Observations on body length and weight: No body weight and length was determined
- Other biological observations: No
- Mortality of control: No
- Adverse effects control: No immobilisation was observed for control animals
- Any observations that might cause a difference between measured and nominal values: No. All tested concentration levels were clearly dissolved throughout exposure
- Effect concentrations exceeding solubility of substance in test medium: No

Results with reference substance (positive control):

- Results with reference substance valid: yes
- 24-hour EC50: 1.2 mg/L

Reported statistics and error estimates:

The EC50 values could not be calculated by Probit Analysis or Moving Average Interpolation due to the steep concentration-effect relationship. Instead, the EC50 values were calculated by linear interpolation of the immobility between the two consecutive test concentrations with
0 and 60 or 85 % immobility after 24 or 48 hours, respectively, on a semi-logarithmic scale. The 95% confidence limits could not be determined. The 24-hour and 48-hour NOEC, EC0 and EC100 were determined directly from the raw data.

Table 1: Effect of the test item on the Mobility of Daphnia magna

Nominal Test Item Concentration [mg/L]	No. of Daphnids Tested	Immobilized Daphnids after 24 Hours		Immobilized Daphnids after 48 Hours
		No.	[%]	No.	[%]
Control	20	0	0	0	0
6.25	20	0	0	0	0
12.5	20	0	0	0	0
25	20	0	0	0	0
50	20	0	0	0 (20D)	0
100	20	12 (2F)	60	17 (3F)	85

Values in parenthesis: number of mobile test animals with adverse effects

A: daphnids trapped at the water surface

B: daphnids sticking together

C: antennae sticking together

D: daphnids discolored/pale

E: spina stuck

F: slower swimming activity

Table 2: Analytical Results for Test Samples

Sampling Day / Sample Age [d/h]	Nominal Concentration of Test Item Cnom [mg/L]	Measured Concentration of Test Item x [mg/L]	Sample Preparation Factor F	Determined Concentration of Test Item c [mg/L]	% of Nominal Concentration
0/0 (fresh)	Control	n.d.	1.2	< LOQ	n.a.
	25	21.6	1.2	25.9	103
	50	42.9	1.2	51.4	103
	100	85.3	1.2	102	102
2/48 (aged)	Control	n.d.	1.2	< LOQ	n.a.
	25	21	1.2	25.2	101
	50	41.7	1.2	50.0	100
	100	82.8	1.2	99.3	99

n.d. = no test item detected

n.a. = not applicable

LOQ: 0.23 mg/L

Remark: The tabulated values of the samples represent rounded results obtained by calculation using the exact raw data.

Validity criteria fulfilled:

yes

Conclusions:

The test item had acute toxic effects on Daphnia magna in a 48-hour static test. The 48-hour EC50 was calculated to be 75 mg/L (the 95% confidence limits could not be determined).

Executive summary:

The acute toxicity of the test item on Daphnia magna was determined in a 48-hour static test according to the OECD Guideline for Testing of Chemicals, No. 202 (2004) and the Commission Regulation (EC) No. 440/2008, Part C.2. The nominal test item concentrations tested were 6.25, 12.5, 25, 50 and 100 mg/L. Additionally, a control (test water without test item) was tested in parallel. The measured concentrations of the test item in the test media of the test concentrations from 25 to 100 mg/L were between 102 and 103 % of the nominal values at the start of the test and between 99 and 101 % at the end of the test. Thus, the test item was stable in the test media over the test period of 48 hours. Therefore, the endpoint values were related on the nominal concentrations of the test item. The 48-hour EC50 was calculated to be 75 mg/L (the 95% confidence limits could not be determined). In conclusion, the test item had acute toxic effects on Daphnia magna in a 48-hour static test.

Description of key information

An EC50 of 75 mg/L (48 h) was determined with a short-term toxicity test in daphnia.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

75 mg/L

Additional information

The acute toxicity of the test item on Daphnia magna was determined in a 48-hour static test according to the OECD Guideline for Testing of Chemicals, No. 202 (2004) and the Commission Regulation (EC) No. 440/2008, Part C.2. The nominal test item concentrations tested were 6.25, 12.5, 25, 50 and 100 mg/L. Additionally, a control (test water without test item) was tested in parallel. The measured concentrations of the test item in the test media of the test concentrations from 25 to 100 mg/L were between 102 and 103 % of the nominal values at the start of the test and between 99 and 101 % at the end of the test. Thus, the test item was stable in the test media over the test period of 48 hours. Therefore, the endpoint values were related on the nominal concentrations of the test item. The 48-hour EC50 was calculated to be 75 mg/L (the 95% confidence limits could not be determined). In conclusion, the test item had acute toxic effects on Daphnia magna in a 48-hour static test.