4-Ethoxy-2,3-difluoro-4'-methyl-1,1'-biphenyl

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:

Mar 25 - Jun 20, 2019

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:

At the start of the exposure and at the renewal (0 and 24 h), samples of the freshly prepared test item concentrations were taken and analyzed.
At renewal and at the end of the exposure (24 and 48 h), sampled of the 24 h old media were taken directly fron the test vessels and analyzed.

Vehicle:

yes

Remarks:

dilution water

Details on test solutions:

The study was conducted under semi-static conditions over a period of 48 hours with a saturated solution of the test item and a further four dilution levels (nominal: 6.25 – 12.5 – 25.0 – 50.0 - 100 %) of the saturated solution prepared in a geometric series with a separation factor of 2. The saturated solution was prepared following the recommendations of the OECD guidance document on aquatic toxicity testing of difficult substances and mixtures (OECD series on testing and assessment no. 23, ENV/JM/MONO(2000)6/REV1).
The saturated solution had a positive Tyndall effect and was slightly turbid throughout the exposure. The further concentration levels (6.25 to 50 % of the saturated solution) were visually clear throughout the exposure.
Twenty daphnids (divided into 4 replicates with 5 daphnids each) were exposed to each concentration level and the control.
The concentrations of the test item were analytically verified via HPLC-DAD in the fresh media of all concentration levels and in the control at the start of the exposure and at the renewal (0 and 24 hours) as well as in the 24-hours old media at the renewal and at the end of the test (24 and 48 hours).

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna STRAUS (Clone 5)
- Source: Institut für Wasser-, Boden und Lufthygiene (WaBoLu), Berlin, Germany
- Age: < 24 h

FEEDING DURING TEST
- Food type: 5 x per week ad libitum with a mix of unicellular green algae

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

0 h: 254 mg CaCO3/L
24 h: 266 mg CaCO3/L

Test temperature:

19.8 - 20.1 °C

pH:

0 h: 7.62
24 h: 7.24

Dissolved oxygen:

0 h: 8.66 mg/L
24 h: 8.53 mg/L

Conductivity:

0 h: 668 µS/cm
24 h: 653 µS/cm

Nominal and measured concentrations:

nominal: 6.25, 12.5, 25.0, 50.0, 100.0 mg/L
measured: 0.156, 0.206, 0.512, 0.905, 1.92 mg/L

Details on test conditions:

Test vessels: Glass beakers, 50 mL capacity, loosely covered with watch glasses
Test volume: 20 mL
Number of daphnids and replicates: 20 daphnids, divided into 4 replicates, each with 5 daphnids were used for each concentration level and control.
Application: 20 g test solution per replicate was weighed out into each test vessel. This corresponds to 20 mL per test vessel. The daphnids were inserted with a samll amount of dilution water (start of the exposure) or test solution (water renewal) by pipette.
Renewal of the test solutions: The test solutions were renewed after 24 h. For this purpose, a second set of test vessels was filled with the freshly prepared test solutions and the daphnids were transferred by pipette.

Reference substance (positive control):

yes

Remarks:

potassium dichromate; in a periodically (once per months) conducted test to prove validity of test system and conditions

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

513 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: no
- Observations on body length and weight: 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):

EC50-Value (with 95 % confidence limits) of the reference item potassium dichromate: EC50 = 2.03 mg/L (1.00 -4.00)

1) Immobilization Rates after 24 and 48 hours of Exposure in the Definitive Test

Geometric mean measured test item concentration [µg/L]	IMMOBILIZATION [%]
	24 hours					48 hours
	Replicates					Replicates
	1	2	3	4	MV	1	2	3	4	MV
1.92	40	100	80	20	60	100	100	100	100	100
0.905	0	100	40	80	55	80	100	100	100	95
0.512	0	0	0	0	0	40	60	60	40	50
0.260	0	0	0	0	0	0	0	0	0	0
0.156	0	0	0	0	0	0	0	0	0	0
Control	0	0	0	0	0	0	0	0	0	0

2) Measured Concentrations during the Definitive Test

Sampling	Fresh media, 0 hours	Old media, 24 hours		Fresh media, 24 hours	Old media, 48 hours
Dilution level of the saturated solution [%]	Test material
	Meas. conc. [mg/L]	Meas. conc. [mg/L]	%	Meas. conc. [mg/L]	Meas. conc. [mg/L]	%	Geometric mean measured concentration [mg/L]
100	1.52	0.542	36	8.25	2.00	24	1.92
50.0	1.07	0.257	24	5.60	0.436	8	0.905
25.0	0.474	0.175	37	2.77	0.299	11	0.512
12.5	0.182	0.101	56	1.35	0.183	14	0.260
6.25	0.0987	0.0554	56	0.731	0.147	20	0.156
Control	< LOQ	< LOQ		< LOQ	< LOQ

Meas. conc.    = measured concentration of the test item, enrichment and dilution factors taken into account

%                      = percentage of the initially measured concentration of the test item

LOQ                 = limit of quantification of the analytical method (1 µg test item/L)

Validity criteria fulfilled:

yes

Conclusions:

The EC50 (48h) based on the geometric mean measured concentrations of the test item was at 0.513 mg/L (95 % confidence limits: 0.481 – 0.544 mg/L).

Executive summary:

The information for this endpoint study record was obtained from an experimental study. The OECD GLP criteria were met and the methods applied are fully compliant with OECD TG 201.

The study was conducted under semi-static conditions over a period of 48 hours with a saturated solution of the test item with a nominal loading of 100 mg test item/L and further four dilution levels (nominal: 6.25 – 12.5 – 25.0 – 50.0 - 100 %) of the saturated solution prepared in a geometric series with a separation factor of 2.

Twenty daphnids (divided into 4 replicates with 5 daphnids each) were exposed to each dilution level and the control. The concentrations of the test item were analytically verified via HPLC-DAD in the fresh media at the start of the exposure and at the renewal of the test solutions (0 and 24 hours) and in the old media at the renewal and at the end of the test (24 and 48 hours) in all dilution levels and in the control. The geometric mean measured concentrations are 0.156 - 0.206 - 0.512 - 0.905 - 1.92 mg/L.

The EC50 (48h) based on the geometric mean measured concentrations of the test item was at 0.513 mg/L (95 % confidence limits: 0.481 – 0.544 mg/L).

Description of key information

The EC50 (48h) based on the geometric mean measured concentrations of the test item was at 0.513 mg/L (95 % confidence limits: 0.481 – 0.544 mg/L).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

513 µg/L

Additional information

The information for this endpoint study record was obtained from an experimental study. The OECD GLP criteria were met and the methods applied are fully compliant with OECD TG 201.

The study was conducted under semi-static conditions over a period of 48 hours with a saturated solution of the test item with a nominal loading of 100 mg test item/L and further four dilution levels (nominal: 6.25 – 12.5 – 25.0 – 50.0 - 100 %) of the saturated solution prepared in a geometric series with a separation factor of 2.

Twenty daphnids (divided into 4 replicates with 5 daphnids each) were exposed to each dilution level and the control. The concentrations of the test item were analytically verified via HPLC-DAD in the fresh media at the start of the exposure and at the renewal of the test solutions (0 and 24 hours) and in the old media at the renewal and at the end of the test (24 and 48 hours) in all dilution levels and in the control. The geometric mean measured concentrations are 0.156 - 0.206 - 0.512 - 0.905 - 1.92 mg/L.

The EC50 (48h) based on the geometric mean measured concentrations of the test item was at 0.513 mg/L (95 % confidence limits: 0.481 – 0.544 mg/L).