Isotridecanol, ethoxylated

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:

2020-06-03 to 2020-06-05

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:

adopted 13. April 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: fresh media at 0 and 24 h and aged media at 24 and 48 h
- Sampling method: Samples were taken directly from the test vessels.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: WAF acc. to OECD guidance document No. 23 (2018). A WAF with a nominal loading rate of 5 mg/L was prepared. This dispersion was shaken for 24 hours with 20 rpm at room temperature. After completion of shaking and a separation phase
of at least 1 hour standing at room temperature, the WAF was removed by siphoning from the middle of the glass flask. Undissolved particles were removed by membrane filtration (membrane filter 0.45 μm, RC, Macherey-Nagel). The filter was saturated in order to avoid adsorption during the filtration. The first 25 mL of the filtrate were discarded. The filtration was interrupted for 10 minutes to allow adsorption and saturation of the filter material with dissolved test item. Thereafter, the filtration was continued. The next 25 mL were discarded. During filtration, the filter was always kept covered. The five loading rates were prepared out of the WSF (nominal loading 5.00 mg/L) by dilution.
- Evidence of undissolved material (e.g. precipitate, surface film, etc.):
no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Age at study initiation (mean and range, SD): < 24 h
- Source: bred at testing facility, originally obtained from: Institut für Wasser-, Boden- und Lufthygiene, Berlin, Germany
- Feeding during test : no

Breeding:
- Breeding conditions (same as test or not): same
- Type and amount of food: ad libitum with a mix of unicellular green algae, e.g. Pseudokirchneriella subcapitata and Desmodesmus subspicatus.
- Feeding frequency: at least 5 times a week

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

291 - 303 mg CaCO3/L

Test temperature:

21.6 - 21.8°C

pH:

7.19 - 7.76

Dissolved oxygen:

6.07 - 8.63 mg/L

Conductivity:

626 - 646 μS/cm

Nominal and measured concentrations:

Nominal loading rate: 0.313, 0.625, 1.25, 2.50, 5.00 mg/L
Geometric mean measured concentrations: 0.269, 0.530, 1.07, 1.98, 3.97 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers
- Type (delete if not applicable): loosely covered with watch glasses
- Material, size, headspace, fill volume: 4 (ID) x 7 (H) cm, 50 mL capacity, fill volume 20 mL
- Aeration: no
- Renewal rate of test solution (frequency/flow rate): every 24 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
- Source/preparation of dilution water: Elendt M4
- Culture medium different from test medium: no
- Intervals of water quality measurement: daily

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16/8 hours light/dark cycle
- Light intensity: Diffuse light, light intensity of max. 1500 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mobility after 0, 24 and 48 h


RANGE-FINDING STUDY
- Test concentrations: 0.100, 1.00 and 10.0 mg/L.
- Results used to determine the conditions for the definitive study: no immobilisation at 0.1 and 1 mg/L. 100% immobilisation at 100 mg/L after 24 h.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

0.64 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: confidence limits: 0.342 – 1.20

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

0.544 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: confidence limits: 0.290 – 1.03

Details on results:

- Mortality of control: no

Results with reference substance (positive control):

EC50 (48 h): 2.16 mg/L (CL: 1.00 - 4.00 mg/L). Date: 2020-05-12 to 2020-05-13

Reported statistics and error estimates:

Excel, MICROSOFT CORPORATION
GraphPad Prism, Version 5.03, GraphPad Software, Inc.

Table 1: Absolute Numbers of immobile Daphnids after 24 and 48 hours of exposure in the 2nd

Definitive Test

Nominal loading rate of the test item in the WSF [mg/L]	NUMBER OF IMMOBILE DAPHNIDS / TOTAL NUMBER OF DAPHNIDS
	24 hour	48 hours
5.0	20/20	20/20
2.5	20/20	20/20
1.25	12/20	20/20
0.625	0/20	6/20
0.313	0/20	0/20
control	0/20	0/20

Table 2: Measured Concentrations of the Test Item Isotridecanol, ethoxylated (2EO) during the 2nd

Definitive Test

Nominal loading rate of the test item in the WSF [mg/L]	Fresh media, 0 hours	Old media, 24 hours		Fresh media, 24 hours	Old media, 48 hours		Geometric mean measured test item concentration [mg/L]
	Meas. conc. [mg/L]	Meas. conc. [mg/L]	%	Meas. conc. [mg/L]	Meas. conc. [mg/L]	%
5.0	4.48	3.52	79	Not applicable, due to 100% mortality			3.97
2.5	2.22	1.76	79				1.98
1.25	1.12	1.06	95	1.12	0.997	89	1.07
0.625	0.694	0.476	69	0.531	0.449	85	0.530
0.313	0.368	0.226	62	0.280	0.226	81	0.269
control	< LOQ	< LOQ		< LOQ	< LOQ		< LOQ

Table 3: Validity criteria for OECD 202.

Criterion from the guideline	Outcome	Validity criterion fulfilled
In the control, including the control containing the solubilising agent, not more than 10% of the daphnids should have been immobilized.	0%	yes
The dissolved oxygen concentration at the end of the test should be ≥ 3 mg/L in control and test vessels.	≥ 8.30 mg/L	yes

 

 

Validity criteria fulfilled:

yes

Remarks:

Please refer to "Any other information on results incl.. tables"

Description of key information

EL50 (48h): 0.544 mg/L (geom. mean measured, OECD 202)

Additional information

One semi-static study on the acute toxicity of Isotridecanol, ethoxylated, < 2.5 EO to aquatic invertebrates is available. The study was conducted according to OECD 202 (GLP) with nominal loading rates of 0.313, 0.625, 1.25, 2.50, 5.00 mg/L (WAF). The test medium was renewed every 24 hours. An analytical dose verification by LC-MS/MS measurements in fresh and aged media was performed. The geometric mean measured concentrations were 0.269, 0.530, 1.07, 1.98, 3.97 mg/L. An immobilisation rate of 100% after 24 hours was observed at nominal loading rates of 2.5 and 5.0 mg/L respectively. At a nominal loading rate of 1.25 mg/L 100% of Daphnids were immobilised after 48 hours. Based on the geom. mean measured concentrations an EL50 (48 h) of 0.544 mg/L was determined.