2-(1-ethylpentyl)-1,3-dioxolane

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:

25 - 30 April 2017

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

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: This stock solution and dilutions of this “stock solution” by 1:2, 1:4, 1:8, 1:16 were prepared for testing. Additionally, a control was tested in parallel. These dilutions corresponded to the following mean measured concentrations of the test item: 66.3, 31.1, 15.3, 7.94 and 3.77 mg test item/L, and a control.
- Sampling method: Duplicate samples from the freshly prepared test media of all test concentrations and the control were taken at the start of the test and at day 1. For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, duplicate samples from the aged test media of all test concentrations and the control were collected at day 1 (after 24 hours of exposure) and at the end of the test by pouring together the contents of the test beakers of each treatment
- Sample storage conditions before analysis: All samples were extracted stand-by immediately after sampling and were stored at 4 ± 4°C until analysis. The remaining parts of the extracts were stored deep frozen (≤ -20°C) and will be kept stored up to the date of the final report.
- Analysis: The concentrations of the test item were analysed in the duplicate test media samples from all test concentrations, and in the duplicate control samples, from both sampling times (0 and 48 hours).

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test item is not well soluble in test medium. To avoid physical effects of undissolved test item on the daphnids, no concentrations above the solubility limit of the test item in test water was tested.
Before test start and before the test medium renewal, a ´stock solution´ (nominal 100 mg/L) of test material in test medium was prepared as close to the water solubility limit as possible by dissolving 200.2 and 198.2 mg test item into 2002 and 1982 mL test water. The test medium was stirred with an excess of test material in a vessel with minimum headspace for 2 hours. Afterwards the test medium was allowed to settle for at least 1 hour until phase separation. This ´stock solution´was withdrawn from a tap at the center of the vessel, after first flushing the tap and tubing with a small aliquot, and then mixed with test medium to produce the desired set of test concentrations. Care was taken to avoid any loss of the test item by volatilisation during transfer/handling steps.
- Controls: test water without test substance
- Evidence of undissolved material: there were no remarkable observations.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna (Straus)
- Strain/clone: clone 5
- Source: test facility's in-house laboratory culture
- Feeding during culture:
* Food type: green algae (Desmodesmus subspicatus)
* Frequency: daily
- Feeding during test: no
- Age at study initiation: young daphnids with an age of 1.5 to 19.25 hours

ACCLIMATION
- Acclimation period: not necessary, since the test was performed in the same medium as the culturing

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:
The daphnids were bred in the laboratories of ibacon under similar temperature and light conditions as used in the test. The cultivation of the parental daphnids was performed in Elendt M4 medium. The test organisms were not first brood progeny.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

no

Hardness:

250 mg/L (as CaCO3)

Test temperature:

19.4 to 20.2 °C in the freshly prepared media;
19.5 to 20.3°C in the aged test media

pH:

8.1 to 8.4 in the freshly prepared media;
8.1 to 8.2 in the aged test media

Dissolved oxygen:

8.5 to 9.1 mg/L in the freshly prepared media;
8.5 to 8.7 mg/L in the aged test media

Conductivity:

< 5 μScm^-1

Nominal and measured concentrations:

The test item is not well soluble in test medium. To avoid physical effects of undissolved test item on the daphnids, no concentrations above the solubility limit of the test item in test water was tested. Before test start and before the test medium renewal, a ´stock solution´ (nominal 100 mg/L) of test item in test medium was prepared as close to the water solubility limit. This stock solution and dilutions of this “stock solution” by 1:2, 1:4, 1:8, 1:16 were prepared for testing. These dilutions correspond to following mean measured concentrations of the test item: 66.3, 31.1, 15.3, 7.94 and 3.77 mg test item/L, and a control.

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers of approximately 110 mL volume containing as much test medium as possible (i.e. the remaining head space was reduced to a technical possible minimum of some mL), kept closed during the whole period of the study with a conical glass stopper to avoid loss of the test item due to volatilisation.
- Aeration: no
- Renewal rate of test solution (frequency): 1 renewal after 24 hours
- 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 according to OECD202
- Alkalinity: 0.9 mmol/L
- Culture medium different from test medium: no
- Intervals of water quality measurement: temperature, pH-values and dissolved oxygen concentrations were determined in all freshly prepared and aged test media of each treatment group

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light : 8 h dark
- Light intensity: 240 to 440 lux

EFFECT PARAMETERS MEASURED: mobility (at 24 and 48 hours)

RANGE-FINDING STUDY
- Test concentrations: not specified in the report
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate (January 2017)

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

17.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Remarks on result:

other: 95% C.I. 14.1 - 20.9 mg/L

Details on results:

- Behavioural abnormalities: no
- Mortality of control: 1 animal was immobile after 48 hours
- Other adverse effects control: 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
- Other:
In the freshly prepared test media at the start of the test and at the renewal of the test media 63% of the nominal test concentrations were found (average of all test concentrations). In the aged test media after 24 and 48 hours test duration, 63% of the nominal value was determined (average of all test concentrations).
During the test the test organism was exposed to a mean of 63% of nominal.

Results with reference substance (positive control):

- Results with reference substance: valid
- Dose-response test: yes; tested concentrations: stock solution of 100 mg/L and the dilutions: 1:10, 1:100 and 1:1000
-The main test: 24h-EC50 = 32.4 mg/L (no 95% C.I. determinable); 48h-EC50 = 17.1 (95% C.I. 14.1 - 20.9 mg/L)
- Other: the sensitivity of the daphnids was consistent with the level proposed by the OECD 202 guideline (i.e. 24h-EC50 between 0.6 and 2.1 mg potassium dichromate/L, which was 1.48 mg/L)

Reported statistics and error estimates:

The 24-hour and 48-hour EC50 and the 95 % confidence limits were calculated by probit analysis.
The slope function (after Litchfield and Wilcoxon) was derived from the slope, b, of the linearised Probit function and computes as S = 10^(1/b); small values refer to steep concentration/response relationships and large ones to flat relationships.
The software used to perform the statistical analysis was ToxRat Professional, Version 3.2.1, ToxRat Solutions GmbH.

Cumulative Immobilization Data and Observations in the Definitive Test

Geometric mean measured  Concentration [mg/L]	No. of Daphnia tested	No. of immobilized Daphnia after		% of immobilized Daphnia after
		24 h	48 h	24 h	48 h
Control	20	1	1	5	5
3.77	20	0	0	0	0
7.94	20	0	1	0	5
15.3	20	0	8	0	40
31.1	20	8	18	40	90
66.3	20	20	20	100	100

 

Summary of Analytical Results

Nominal	Fresh test media (0h)			Aged test media			Mean measured
Test Concentration	% of	RSD		% of	RSD		Concentration^2
[mg test item/L]	nominal^1	[%]	n	nominal^1	[%]	n	[mg/L]
Control	n.a.	n.a.	4	n.a.	n.a.	4	n.a.
1 : 16 dilution	61	19	4	60	20	4	3.77
1 : 8 dilution	64	13	4	64	18	4	7.94
1 : 4 dilution	62	12	4	61	19	4	15.3
1 : 2 dilution	63	11	4	61	17	4	31.1
'stock solution'	65	8	4	68	14	4	66.3

¹mean value of all measured samples per treatment group
²mean measured value calculated using initial mean recovery and aged mean recovery rates per treatment group
RSD: relative standard deviation per treatment group
n: number of analysed samples
n.a.: not applicable

Validity criteria fulfilled:

yes

Remarks:

1) In the control, no daphnids became immobilised or showed other signs of disease or stress. 2) The oxygen concentration at the end of the test was ≥3 mg/L in control and test vessels (which was ≥8.5 mg/L).

Conclusions:

The 48h-EC50 value to Daphnia magna was 17.1 mg/L based on geometric mean measured concentrations.

Executive summary:

A study was performed to assess the acute toxicity of the substance to Daphnia magna. The study was conducted in accordance with OECD Guideline for Testing of Chemicals No. 202 and GLP under semi-static conditions. Based on the results of a range-finding test, the following nominal concentrations were tested in the definitive test: untreated control, an aqueous solution of test item in test media with a concentration as close to saturation as possible (100 mg/L nominal) as highest test concentration and dilutions of the highest concentrations of 1:2, 1:4, 1:8 and 1:16. The measured concentrations were: 66.3, 31.1, 15.3, 7.94 and 3.77 mg test item/L. For each concentration and a control group, twenty Daphnia magna (less than 24 hours old) were exposed for 48 hours in air-tight closed vessels. The incidence of immobilisation was recorded for each test and control group at 24 hours and at 48 hours. Samples taken from all concentrations at the start and the end of both 24 -hour renewal periods were analysed with a validated GC-FID method. In the freshly prepared test media at the start of the test and at the renewal of the test media 63% of the nominal test concentrations were found (average of all test concentrations). In the aged test media after 24 and 48 hours test duration, 63% of the nominal value was determined (average of all test concentrations).

Since test concentrations did not remain stable during the 24 -hour renewal periods, geometric mean measured concentrations were calculated. The range tested based on geometric mean measured concentrations was

66.3, 31.1, 15.3, 7.94 and 3.77 mg test item/L.

The 48h-EC50 value to Daphnia magna was 17.1 mg/L based on geometric mean measured concentrations.

Description of key information

A study was performed to assess the acute toxicity of the substance toDaphnia magna. The study was conducted in accordance with OECD Guideline for Testing of Chemicals No. 202 and GLP under semi-static conditions. Based on the results of a range-finding test, the following nominal concentrations were tested in the definitive test: untreated control, an aqueous solution of test item in test media with a concentration as close to saturation as possible(100 mg/L nominal) as highest test concentration and dilutions of the highest concentrations of 1:2, 1:4, 1:8 and 1:16. The measured concentrations were:66.3, 31.1, 15.3, 7.94 and 3.77 mg test item/L. For each concentration and a control group, twentyDaphnia magna(less than 24 hours old) were exposed for 48 hours in air-tight closed vessels. The incidence of immobilisation was recorded for each test and control group at 24 hours and at 48 hours. Samples taken from all concentrations at the start and the end of both 24 -hour renewal periods were analysed with a validated GC-FID method.In the freshly prepared test media at the start of the test and at the renewal of the test media 63% of the nominal test concentrations were found (average of all test concentrations). In the aged test media after 24 and 48 hours test duration, 63% of the nominal value was determined (average of all test concentrations).

Since test concentrations did not remain stable during the 24 -hour renewal periods, geometric mean measured concentrations were calculated. The range tested based on geometric mean measured concentrations was

66.3, 31.1, 15.3, 7.94 and 3.77 mg test item/L.

The 48h-EC50 value toDaphnia magnawas 17.1 mg/L based on geometric mean measured concentrations.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

17.1 mg/L